[HN Gopher] Building a Personal VoIP System
       ___________________________________________________________________
        
       Building a Personal VoIP System
        
       Author : matthews2
       Score  : 277 points
       Date   : 2023-05-27 07:18 UTC (15 hours ago)
        
 (HTM) web link (www.sacredheartsc.com)
 (TXT) w3m dump (www.sacredheartsc.com)
        
       | gamedna wrote:
       | Having gone down this road many times with freepbx, asterisk,
       | etc.. I ultimately settled on just using voip.ms and connecting
       | phones/sip clients directly to their internal sub-accounts with
       | voicemail. They have enough features for most users so you don't
       | need to worry about running your own PBX.
        
         | [deleted]
        
         | jonpurdy wrote:
         | I have been using voip.ms since 2015 for my phone service.
         | Multiple numbers (DIDs) pointing to an IVR where callers must
         | press 1 to connect to me (totally avoids robocalls). Plus
         | voicemail (transcribed and emailed to me).
         | 
         | One issue with voip on mobile (iOS in my case) is that I would
         | often miss calls due to late push notifications and timing out.
         | So recently I set up a calling queue that rings/pushes my phone
         | a few times instead of just once (queue timeout to 30 seconds
         | before hitting voicemail).
         | 
         | Basically, if you want the control FreeSwitch and Asterisk
         | offer but don't want to self-host, voip.ms is the best way to
         | go.
        
         | ivr-eric wrote:
         | Same here. 3 businesses, only 1 problem in 10 years.
         | 
         | The only thing I have to add: if you need to make telephone
         | calls, the call quality using a SIP phone is much better than
         | using a softphone.
        
           | carlhjerpe wrote:
           | This isn't necessarily true, a computer can speak SIP too,
           | with a good headset it's just as good.
        
             | stavros wrote:
             | I disagree. Yes, in theory, an agent is an agent, but in
             | practice I have never in my life at any point seen computer
             | hardware that comes anywhere close to the usability of a
             | Polycom device.
        
             | zerox7felf wrote:
             | Yeah, I would second this. In SIP a UA is a UA. So long as
             | your softphone is good and your microphone is as well,
             | there shouldn't be any difference. Although I would suspect
             | the general experience may be that people with softphones
             | more often will have terrible microphones for their PC...
        
       | sydney6 wrote:
       | Has someone good experience with a VoIP-Provider (not OVH or
       | Sipgate) in Europe?
        
         | folmar wrote:
         | Nfon works fine but the panel is absymal at best.
        
         | MattJ100 wrote:
         | I'm eagerly awaiting jmp.chat to branch out into Europe (they
         | have plans, but no concrete timeline).
         | 
         | I'm curious why not sipgate, which I currently use, or Twilio
         | which I half-use (it mostly forwarded to my own Asterisk
         | server, which needs some attention).
        
         | dominikmauritz wrote:
         | Shameless plug. I'm co-founder and CEO of vio:networks -
         | https://www.vionetworks.de
         | 
         | We offer a virtual PBX based on Asterisk, Kamailio and
         | Matrix/Element in Germany.
        
         | progx wrote:
         | Use fonial since 2 years without any problem. It has a good
         | configuration options with a simple backend interface.
        
         | linker3000 wrote:
         | Do you have any specific issues with Sipgate? I only have a
         | couple of numbers with them and don't use them much but am
         | curious what their reputation is like.
        
           | sydney6 wrote:
           | I can't say anything about sipgate's reputation, as i haven't
           | used their service. It just has been an issue with limited
           | service availability in my country (BE)..
        
           | gingerlime wrote:
           | I just saw that they might discontinue their starter plan[0]
           | as they focus on business. I can understand that residential
           | voip is pretty much dead.
           | 
           | [0] https://help.sipgate.de/hc/de/articles/4407798852113-sipg
           | ate...
        
         | zajio1am wrote:
         | I have very good experience with Odorik (
         | https://www.odorik.cz/?jazyk=en ).
        
       | ttul wrote:
       | If only there was an equivalent for building your own home
       | GSM/LTE network. When around the house, I would love to connect
       | to my own private cellular network. Not only is coverage poor
       | where I live, but this would allow me to route calls in
       | sophisticated and useful ways, because the backplane of modern
       | cellular networks is VoIP.
        
         | singpolyma3 wrote:
         | I expect you would need a spectrum license for that :)
        
       | zokier wrote:
       | People still actually make phone calls? I mean its neat that you
       | can run your own voip, but I struggle to imagine it getting used
       | much or being worth even $5/month
        
         | rjsw wrote:
         | I'm just about to ask for my landline to be disconnected, no
         | sense in paying for something I hardly ever use, won't bother
         | porting the number to VoIP. Will either just keep the copper
         | pair for VDSL or switch to FTTP.
         | 
         | The only person that I did call using the landline is my
         | father, but his VoIP system is unreliable.
        
         | PopAlongKid wrote:
         | When I'm conversing with family or friends by phone using my
         | VoIP, and the connection starts getting bad, I always volunteer
         | that the problem is not on my end, since my connection is
         | wired.
        
         | forgotmypw17 wrote:
         | Yes, there are many people for whom voice phone is the
         | preferred method of contact, and I accommodate them because
         | they're important to me.
        
         | hermannj314 wrote:
         | People still read newspapers, ride horses, plant crops by hand,
         | and dress up for renaissance faires.
        
         | ocdtrekkie wrote:
         | I want to set something like this up myself, probably less for
         | external calling than as an in-home intercom. Public dialing
         | might be handy just so it can easily include cell phones.
        
       | rglullis wrote:
       | So, maybe one of the VoIP experts that showed up on this thread
       | can help me with one doubt...
       | 
       | Let's say that I have a LDAP server where I manage user accounts,
       | and I want people to be able to call each other with any SIP-
       | enabled phone. I am not interested in voicemail/IVRs/any type of
       | "voice application" on top of that. Do I really need
       | Asterisk/FreeSWITCH or can I just go buy by setting up something
       | like Kamailio?
        
         | codeslinger wrote:
         | Kamailio is what is called a Session Border Controller. Its
         | primary purpose is to provide protection and some lightweight
         | filtering for the media servers/PBXs behind it. Once you want
         | "advanced" features like voicemail, parking, hunt groups,
         | three-way calling, etc, you will need to use a PBX like
         | FreeSWITCH (recommended) or Asterisk (not) behind it anyway. If
         | you're only running a single machine, an SBC isn't really worth
         | the trouble.
        
           | rglullis wrote:
           | > Once you want "advanced" features like voicemail, parking,
           | hunt groups, three-way calling.
           | 
           | Right, but what I am saying is that I _don 't_ want any of
           | those features. At least not yet.
           | 
           | I just want to give my customers a sip address ( _username_
           | @communick.com) where they can call other SIP addresses. In
           | that case, is that a PBX still needed?
        
             | jjrh wrote:
             | You certainly can use Kamailio but it will be much
             | easier/faster to get something going in Asterisk.
             | 
             | You don't need to run any of the advanced features in
             | Asterisk (and can completely unload the modules if you
             | want).
        
       | michael_michael wrote:
       | I've built my own business VoIP system -- a few times over. I've
       | used Asterisk and FreePBX (the free-ish GUI built on Asterisk),
       | but settled on Asterisk for stability. At one point FreePBX
       | pushed out an update that took down my system for a couple of
       | days and baffled me until I read the FreePBX forums and saw
       | similar complaints from other users.
       | 
       | If you want a week-ish long project, go for the full mid-2000s,
       | boingboing and slashdot experience: buy the dead tree version of
       | the O'Reilly Asterisk book, which has been kept up to date and is
       | still an wonderful resource. Follow it until you have the
       | Enterprise-grade phone system of your dreams.
       | 
       | I even hired Allison "The Voice of Asterisk" [0] to do our phone
       | tree voice prompts. Her prices were very reasonable for a small
       | batch of prompts, and it's surreal hearing the same lady that
       | does the IVR for your bank and cable company do your own voice
       | prompts.
       | 
       | I use Twilio for my SIP trunking, and it has nice fallback
       | features in case the Asterisk system needs to go down for
       | maintenance or the like. Costs about $20/month for a dozen or so
       | users and fairly frequent calls/SMS.
       | 
       | [0]: https://www.theivrvoice.com/
        
       | TacticalCoder wrote:
       | Ah good memories! Even though I knew nothing about VoIP I
       | installed, years ago, one at my wife's little SME using "RasPBX"
       | (a distro made of Raspbian + FreePBX + Asterisk) running on a...
       | Raspberry Pi 1 (maybe a Pi 2 but I'm pretty sure it was a 1). The
       | Pi was booting from the SD card but everything was running on an
       | external HDD.
       | 
       | I did put six Cisco VoIP phones and all was working fine as long
       | as no more than four phones were used simultaneously (which never
       | happened). It worked for years like that and wife ended up
       | selling her SME with these VoIP phones still hooked to the RPi 1.
       | We warned them that that thing was kinda a hack ; )
       | 
       | For anyone hesitating: it's not hard to set up. Find a provider
       | to get a SIP trunk, configure the thing, backup the config (I
       | just imaged the entire drive), and you're good to go for a very
       | long time.
       | 
       | It's simple, reliable, stuff that usually won't move under your
       | feet.
        
         | revskill wrote:
         | It's surprising that you could configure everything without
         | hardware/software compatability issues.
        
           | TacticalCoder wrote:
           | Well I basically used a a Linux distribution made precisely
           | for this: it was called "RasPBX" back then, IIRC. The
           | hardware was simple: a Pi 1, an external HDD hooked through
           | USB to the Pi and Cisco VoIP phones. That Linux distro
           | already took care of picking software components/versions all
           | working fine together and it was tailor made for the Pi. It
           | was pretty plug and play from what I remember.
           | 
           | I'm a software dev, not a sysadmin, but I can find my way
           | around configure Linux machines.
           | 
           | I don't remember it as being particularly complicated. What I
           | do remember for sure though is that once it worked, it worked
           | flawlessly for years.
        
         | jamesmstone wrote:
         | I have a tangentially related problem I have been battling with
         | that you may be able to help me with. I'm moving overseas
         | (Australia to Denmark) and would like to keep my current mobile
         | phone number working for calls and SMS , but use it from afar.
         | I would be able to leave a raspberry pi at a friend's house.
         | Can you use this setup without a SIP provider? Would you need
         | to buy a modem for the raspberry pi?what would you do?
        
           | pseudostem wrote:
           | I have setup a PRI to SIP channel before using elastix (now
           | discontinued and bought by 3CX I think).
           | 
           | This needs investigation, but - Over the top of my head, I
           | think you could probably have some kind of a 4G/5G modem
           | hooked on to an SBC (Pi, APU, etc.) and then forwarded to
           | your SIP line which you can pick over IP (Internet), this
           | should work.
           | 
           | One of the child comments mentioned DID (Direct Inward
           | Dialling). I am no expert, but if your Australian provider
           | supports something similar, you will get the number (friend)
           | who is dialling in, instead of your own Australian number
           | dialling in to your receiver phone. This is useful for caller
           | ID, otherwise it's just like a forwarded call.
           | 
           | Hope this helps.
        
           | singpolyma3 wrote:
           | This is pretty much exactly the problem that we originally
           | created https://jmp.chat to solve, no sip or complex setup
           | needed these days for that use case.
        
             | justsomehnguy wrote:
             | I heard about you ages ago and wanted to use your service
             | ever since. The only problem I don't need it for
             | _anything_. But I 'm glad you you are still there.
        
           | monkey26 wrote:
           | I use Callcentric for this. Ported a land line over years
           | ago. It now has SMS which I can do using the Callcentric app.
           | And it forwards voicemails to me with email. Otherwise I
           | don't use that line for actual calls anymore.
        
           | sokoloff wrote:
           | I've never done it, but look into chan_mobile and a bluetooth
           | dongle to connect a mobile (with your SIM) to asterisk
           | running on a Pi at your friend's place.
        
           | sgc wrote:
           | I would just port my number to twilio and use/write a really
           | basic twilio mobile app. It's a bit risky to rely on a
           | slightly cobbled hardware/software setup that is sitting
           | across the world with no physical access.
        
             | mindslight wrote:
             | Note that one problem with voip providers is the
             | numbers/lines often won't be recognized as valid by snake
             | oil 2FA and the like. So porting to a voip provider only
             | works if your goal is receiving SMS/calls from actual
             | humans or just parking the number for later. But if you're
             | doing it to avoid having to change your number for every
             | service that has an SMS nagwall, it likely won't work.
             | 
             | You can get a modem that will do SMS (eg a Sierra Wireless
             | card), but I don't know if/how they do voice.
             | 
             | Also, I'd shy away from the RPi based on the unreliability
             | of SD cards. It would/will be pretty annoying for your host
             | to go down and you have to travel back to fix it. I suppose
             | if your friend is halfway handy you could keep an image of
             | the machine as installed. Or even take new images remotely
             | (rsync from the raw device a few times in a row?). If the
             | root filesytem goes wonky, have your friend pull the SD
             | card and reimage it.
        
               | EVa5I7bHFq9mnYK wrote:
               | I've been using a voip number for all my sms 2fa needs
               | for the last 5 years while living abroad. I have a dozen
               | banks and other financial institutions plus the irs
               | happily accepting it. Some companies, like openai, wont
               | accept it, for those I just buy single use SMS numbers.
        
               | mindslight wrote:
               | I've had problems with a bunch of places, so it's at
               | least YMMV then. And I'd be wary of transferring an
               | existing number in (as opposed to getting a new voip
               | number and then setting it up).
               | 
               | I'm sure specific services are hit or miss - there really
               | _shouldn 't_ be a problem sending SMS to whatever number
               | a user enters, but paternalistic snake oil salesmen gonna
               | be paternalistic.
               | 
               | I've had the least difficulty with Google Voice (I
               | believe it's impossible to tell "Google Voice" usage from
               | bona fide Fi usage where it's really the users' only
               | phone number). Voip.ms has worked very little for me, to
               | the point of that I don't even try it. Heck I even used a
               | voip.ms number for some online classifieds, and another
               | person using Comcast/Xfinity mobile couldn't text me. I'm
               | not saying this as a slight against Voip.ms itself, from
               | what I've gathered most voip providers will be treated
               | similarly.
               | 
               | One of these days when I get around to it I plan on
               | setting up a wireless modem on a $3/mo paygo plan for my
               | SMS nag needs. With a script that automatically brings
               | the number as close to my paste buffer as possible.
               | 
               | What single use SMS service do you use? I haven't really
               | investigated those.
        
               | Spooky23 wrote:
               | Some services can definitely detect Google Voice. Chase
               | bank won't send SMS to voice.
        
               | singpolyma3 wrote:
               | > I believe it's impossible to tell "Google Voice" usage
               | from bona fide Fi usage where it's really the users' only
               | phone number
               | 
               | These are definitely distinguishable, and some auth
               | service treat them differently. Google Voice numbers come
               | from a different carrier (the one named Bandwidth) than
               | most Fi numbers.
        
               | InvaderFizz wrote:
               | I use a RedPocket (GSMA Flavor) $60/year for my resume
               | and 2FA number as an eSIM.
               | 
               | I turn it on when needed, which is almost never. When not
               | job searching, the voicemail plays the classic "this line
               | has been disconnected" tones and message on repeat for
               | two minutes. WiFi calling means I can use it anywhere I
               | have WiFi.
               | 
               | I get incredibly few spam calls using this strategy.
        
               | rsync wrote:
               | "One of these days when I get around to it I plan on
               | setting up a wireless modem on a $3/mo paygo plan for my
               | SMS nag needs. With a script that automatically brings
               | the number as close to my paste buffer as possible."
               | 
               | This is called a "2FA Mule":
               | 
               | https://kozubik.com/items/2famule/
               | 
               | "A 2FA Mule is a mobile phone configured to forward SMS
               | 2FA codes via email."
        
               | agwa wrote:
               | There are two different reasons companies ask for your
               | phone number, and it's worth distinguishing between them:
               | 
               | The first is for sending a verification code during
               | signup to prevent spammy/abusive signups. In my
               | experience, this is the least likely to work with VoIP
               | numbers because companies often intentionally block VoIP
               | numbers.
               | 
               | The second is for sending 2FA codes during login. My
               | experience with this has been much better. AFAICT,
               | companies do not intentionally block VoIP numbers for
               | this use case. When SMS does fail, there is almost always
               | an option to send the code by voice call, and this is
               | always 100% reliable.
               | 
               | I also have some experience with using a modem with a SIM
               | card to receive SMS. I've used two different models of
               | modem (not Sierra Wireless) and both have been very
               | flaky, often locking up and requiring a power cycle, or
               | having hours-long delays when receiving SMS. I would not
               | call this approach a panacea.
        
             | agwa wrote:
             | Unfortunately, Twilio is no longer a viable option for
             | sending SMS for personal use. If you want to send SMS you
             | have to register a "campaign" and jump through a bunch of
             | hoops that assume you're a company sending a large volume
             | of application-generated messages (e.g. you must disclose
             | samples of the types of messages you intend to send, and
             | get explicit opt-in from recipients). Up until now, I've
             | managed to avoid registering a campaign by instead paying a
             | slightly higher per-message cost, but this is being phased
             | out on July 5. I've been trying out https://jmp.chat (their
             | founder is commenting elsewhere in this thread) and will
             | likely port my number to them.
        
               | rsync wrote:
               | Hmmm ... I think the July 5 deadline is specifically for
               | UK recipients ?
               | 
               | Regardless, your overall impression is correct: Twilio is
               | no longer a hacker/hobbyist/enthusiast option as you
               | cannot (by the letter of the law, at least) send SMS
               | without registering your business entity:
               | 
               | https://twitter.com/rsyncnet/status/1593384850073214976?l
               | ang...
               | 
               | This is very troublesome to me because I have built my
               | own personal telco out of twilio functions and twiml
               | bins, etc., and am heavily reliant on all manner of SMS
               | workflows.
               | 
               | As of this writing (2023-05-27) everything - even SMS
               | delivery to T-Mobile numbers - continues to "just work"
               | but it sounds like I will just wake up one morning to
               | have it all broken ...
        
               | agwa wrote:
               | The deadline is for US recipients:
               | 
               | > * Effective July 5, 2023, all 10DLC phone numbers used
               | to send SMS and MMS messages to U.S. phone numbers must
               | be fully registered to an approved campaign under your
               | brand. Messages sent using unregistered phone numbers
               | will be subject to a gradual increase of message blocking
               | by Twilio, beginning on July 5, 2023, ultimately leading
               | to a full block of all unregistered U.S.-bound messages
               | sent after August 31, 2023.
               | 
               | Source: https://support.twilio.com/hc/en-
               | us/articles/1260800720410-W...
        
         | windexh8er wrote:
         | I believe they're still related but the guys at Nerd Vittles
         | [0] are still doing a PBX in a Box style deployment. Looks like
         | it's called Incredible PBX [1] now. But the last time I ran it
         | it took a lot of considerations around running SIP securely and
         | brought a few of the pieces together. Probably worth a look if
         | you're interested in self-hosting at home or for SMB.
         | 
         | [0] https://nerdvittles.com/ [1]
         | https://wiki.incrediblepbx.com/
        
         | kunwon1 wrote:
         | I've been working with bespoke VOIP/asterisk systems for a
         | decade, I have one bit of advice to add - consider toll fraud.
         | Especially for a system accessible from the internet. If an
         | attacker can figure out how to make calls through your PBX,
         | they can rack up tens of thousands of dollars in tolls over the
         | course of a night.
         | 
         | Most of the integrated FOSS solutions come with fail2ban
         | already configured, it is essential. If you want more peace of
         | mind, a prepaid trunk helps. That means you charge up your sip
         | trunk account, and if someone drains it, it just stops working
         | instead of continuing to drain your bank account.
         | 
         | You can also limit international calling on your trunks, which
         | effectively nullifies the financial drain of this kind of
         | attack (though it's still obviously bad if an attacker can
         | access your system in any way)
        
       | pabs3 wrote:
       | Does anyone have SIP setup on their domain? Are there many spam
       | calls these days?
        
         | deno wrote:
         | Other way around, there are bots testing if they can use your
         | systems for placing spam calls.
        
           | linker3000 wrote:
           | Yep, if I set 'Allow Incoming SIP Messages from SIP Proxy
           | Only' to 'no' (allows direct SIP-SIP calls) on my home VoIP
           | service, I'll get a silent call from '500' about every minute
           | or so.
        
         | Taniwha wrote:
         | I've written about it elsewhere in this thread but I've found
         | that a simple vopice menu that has a message (that might sound
         | like a voicemail to a spammer's dial computer) and that
         | requires people dialing in to press one key stops 99% of
         | spammers
        
         | singpolyma3 wrote:
         | I run a public SIP server, and it gets constantly attacked just
         | like any other public service. Mostly trying to use it to call
         | expensive routes hoping it's unsecured though, not trying to
         | spam local extensions.
        
       | xnyanta wrote:
       | The solution to the NAT issues is simply to use IPv6 and not
       | worry about NAT.
        
         | mnd999 wrote:
         | Yes, that's what I do. Andrews and Arnold offer SIP over ipv6
         | in the UK (and probably further afield).
        
         | systems_glitch wrote:
         | Yeah, it's amazing how many SIP providers don't support IPv6
         | still :/ Total solution, no more headaches.
        
         | deno wrote:
         | Phones need to stay up and at this point in time NAT is more
         | reliable than IPv6, which is probably not even an option most
         | of the time anyway.
        
       | fulafel wrote:
       | Would be interesting to hear why they use v4+nat and face the
       | described problem. First thought was maybe they bought some very
       | old phones without v6 support - but the models he recommends
       | don't seem to have this problem based on a googled datasheet.
        
         | stonewall wrote:
         | (Author here.) Sadly its a lot less interesting: my home ISP
         | still doesn't support IPv6.
        
           | jeroenhd wrote:
           | For what it's worth, and if you're willing to tinker, you can
           | get IPv6 for free through a tunnel as long as your router
           | responds to ICMP: https://tunnelbroker.net/
           | 
           | You can get a bunch of /64s and a /48 for free because HE
           | really wants everyone to have IPv6 available already. Picking
           | the right internet exchange to route from and making Netflix
           | not throw a fit requires some minor experimentation but I've
           | found it to work quite well.
           | 
           | As an added bonus, because of the way IPv6 route
           | advertisements work, you don't have to have a router with
           | tunneling support. You can set up advertisements from any
           | Raspberry Pi or other computer as long as it has outbound
           | connectivity.
        
             | remram wrote:
             | > You can set up advertisements from any Raspberry Pi or
             | other computer as long as it has outbound connectivity.
             | 
             | You mean send the advertisement _and do the SIT tunneling_
             | on that machine?
        
               | jeroenhd wrote:
               | Correct! It's relatively straightforward, actually:
               | https://devzone.nordicsemi.com/nordic/nordic-
               | blog/b/blog/pos...
               | 
               | You use one of the /64 tunnels provided for you to route
               | the /48 tunnel to the rest of your network. You advertise
               | a subnet from your /48 to your local network and if
               | you've got SLAAC enabled on your hosts that's all there
               | is to it.
               | 
               | You may need to mess with the default DNS server to get
               | IPv6 results, though, that depends on whether or not your
               | standard DNS server will respond to AAAA requests. It
               | usually should, but some ISPs don't.
               | 
               | This only works for a flat network, of course. If you've
               | got different routers, you'll need to set up a more
               | complicated setup.
        
             | agwa wrote:
             | The SIP provider would also need to support IPv6 for this
             | to do any good. voip.ms does not: https://wiki.voip.ms/arti
             | cle/FAQ#Do_you_Support_IPV6_with_SI...
        
               | jeroenhd wrote:
               | That's rather silly. Getting IPv6 connectivity is usually
               | the difficult part, and servers are the easiest things to
               | get IPv6 for. I wonder what part of their tech stack is
               | still incompatible after all these years.
        
               | agwa wrote:
               | The quality of VoIP software tends to leave a lot to be
               | desired, in my experience.
               | 
               | None of the 4 VoIP providers I've worked with support
               | IPv6 :-/
        
             | da768 wrote:
             | Last time I tried Tunnelbroker, it caused major performance
             | issues. Not sure it's a good thing for VoIP calls.
        
       | tempaccount1234 wrote:
       | Any recomendable sip Clients for iPhones to Connect to such a
       | system?
        
         | supertrope wrote:
         | Acrobits Groundwire. Counterpath's Bria Mobile. These use push
         | notifications for incoming calls. That way there's no missed
         | calls because the operating system killed the app or battery
         | drain caused by keeping the app running.
        
       | villgax wrote:
       | I'd rather stab myself with WebRTC clients & a signalling+TURN
       | server instead of enduring Asterisk
        
         | mgbmtl wrote:
         | Which clients do you use? And how do you connect to a SIP trunk
         | / DID without Asterisk?
         | 
         | I use WebRTC with Asterisk, and Browser Phone for the client
         | (https://github.com/InnovateAsterisk/Browser-Phone). I don't
         | use it much, but good enough for the rare times I have to use
         | the phone.
        
       | rcarmo wrote:
       | This was sort of a thing in the mid-2000s, and I'm actually
       | surprised to see it again. At the time I expected home routers to
       | become SIP endpoints (and that came to pass with fiber), but they
       | all expose FXO interfaces (jacks) rather than act as proxies for
       | soft phones, so there's a missed opportunity there. But the truth
       | of the matter is that just shipping a DECT phone in a bundle is
       | much easier for the carrier to troubleshoot.
        
         | forgotusername6 wrote:
         | We could have easily been calling eachother by our email (SIP
         | URIs) addresses. It is a shame that instead we got a dozen
         | walled gardens when it comes to making voice/video calls over
         | the internet.
        
           | rsolva wrote:
           | Can you share some resources explaining how this could be set
           | up?
        
             | gormandizer wrote:
             | TRIP/ITAD is/was a framework that I believe was designed to
             | facilitate this. Unfortunately it never took off.
             | https://www.rfc-editor.org/rfc/rfc2871
        
             | brazzledazzle wrote:
             | One way was SIP and SRV DNS records. Seemed like it had
             | some of the problems email has except it's a phone ringing
             | instead of spam.
        
       | orev wrote:
       | Great explanation of the SIP protocol. I've been looking for
       | something that explains it this clearly forever, and this gets
       | right to the point with the high level concept instead of getting
       | immediately bogged down in technical specs.
        
       | systems_glitch wrote:
       | It's worth noting that Asterisk will run on very low-end
       | hardware: for the last 7 or so years, I've been running a small
       | Asterisk box on a VIA C3 Mini-ITX system. System idle power is
       | around 10W. The only reason I chose the VIA C3 system over
       | something newer was that a) I already had it and b) it had a PCI
       | slot (specifically PCI, not PCIe).
       | 
       | The PCI slot let me plug in a Digium TDM800P and add eight POTS
       | lines, either FSX or FXO, for pretty cheap.
        
         | jjrh wrote:
         | You will probably have a harder time finding hardware that
         | won't run asterisk.
        
         | WesolyKubeczek wrote:
         | Today you could have the same average power consumption with an
         | Odroid H3, and probably juggle more quality codecs too. (Well,
         | sans the Digium card; but it's just mindboggling how far we
         | went with power consumption these days.)
         | 
         | I'm wondering how necessary POTS lines actually are these days
         | (and how many connect to VoIP on the telco side). Should depend
         | on the country.
        
           | tomatocracy wrote:
           | The H3 has an M.2 slot and a separate emmc slot. So if you
           | really wanted to use that card perhaps you could use an M.2
           | to PCIe connector and then connect that in turn to a PCIe to
           | PCI adapter/riser. Power might be an issue though.
        
           | systems_glitch wrote:
           | The POTS lines were largely for goofing around, though I did
           | use a FXO port to bring in the local POTS line. Mostly I used
           | the FXS ports to interface a 1A2 KSU to Asterisk to run my
           | old WE 2500 series key station.
           | 
           | 90% of the traffic was handled over SIP or IAX to desk sets
           | or ATAs.
        
           | extinctpotato wrote:
           | These days POTS lines are usually only used for last mile
           | communications so the calls get converted to VoIP on the
           | telco side. Basically it's for backwards compatibility -- the
           | phone lines are already there, a lot of people have phone
           | wiring in their houses and no configuration is required on
           | the consumer's end.
           | 
           | In general the days of having direct electrical connections
           | between two distant telephones are long gone. The telco
           | companies scrapped it when they realized that they could
           | trunk the phone calls from a local branch to the central
           | office using PCM streams over a single cable.
        
             | systems_glitch wrote:
             | Metallic path between two stations that weren't terminated
             | in the same CO has been dead for a _long_ time! I suspect
             | nowadays you 're unlikely to have metallic path outside the
             | frame you land on, if that, unless you're paying for dry
             | pairs.
        
       | irusensei wrote:
       | I've used to live in an inter generational big house (Italians am
       | I right... even if we are not actually born there we still have
       | spaghetti dna). Anyway I've setup one very lightweight asterix
       | instance of statically defined accounts. A few cheap voip phones
       | were installed through the house plus soft phones on personal
       | smartphones.
       | 
       | It was supposed to make things more convenient. Supposed to,
       | because we just kept yelling to convey messages. When I've moved
       | out I've dismantled the system since I wouldn't be there to keep
       | it maintained.
        
       | wnolens wrote:
       | Cool to read someone indulge in this. For others interested with
       | no prior context, also consider FreeSWITCH.
       | 
       | Personal experience:
       | 
       | I spent about 15 months working for a local telecom company,
       | supporting their asterisk servers and developing interactive
       | voice response applications. I was given the opportunity to build
       | their residential voip service (in 2010?) from scratch and
       | despite asterisk being so dominant I prototyped and eventually
       | completed the project using freeSWITCH. I found it to be so much
       | more developer friendly to configure and extend. Being able to
       | build dial plans and implement logic with JavaScript or Lua
       | rather than asterisk's config files was worth it. I suspect this
       | system is still running.
        
         | jelly wrote:
         | I took a look at freeSWITCH's site and it looks like they got
         | bought out. Their documentation is a total mess because the
         | acquiring company has imported lots of wiki pages without much
         | care for how they fit together.
        
           | psim1 wrote:
           | Their wiki has always been a bit of a mess. The company
           | Signalwire is largely the same crew as the original
           | FreeSWITCH team.
        
         | dmpanch wrote:
         | Asterisk from 12th version supports Asterisk REST Interface, no
         | longer need to write configs.
        
           | [deleted]
        
         | danogentili wrote:
         | Asterisk dialplans can also be written in Lua, thanks to the
         | Lua extension!
        
           | singpolyma3 wrote:
           | Yes, this is what I do. The documentation is sometimes a
           | trick to map over, but it's so nice to use a real language
           | for everything else.
        
       | password4321 wrote:
       | Any technology recommendations or examples for integrating VoIP
       | with open source chat platforms like Jitsi, Mumble, etc.?
        
         | singpolyma3 wrote:
         | Jitsi has something built in, I havent used it but I expect
         | it's similar to big blue button which I have done, it runs a
         | freepbx so setting up some extra dialplan rules to get
         | interconnect is possible.
        
       | psim1 wrote:
       | I am one of the few people from my generation to maintain a "land
       | line" (VoIP) and I, too, run it with Asterisk and the FreePBX
       | configuration GUI. FreePBX provides a ton of macros out-of-the-
       | box so that adding unwanted callers to a blacklist or doing phone
       | number lookups is simple, for example. Why bother? Well, I find
       | it interesting and fun, but most of the stuff I like can also be
       | done with Google Voice. So I don't recommend self-hosting a phone
       | system unless you are really into the idea and want to spend a
       | decent amount of time learning telecom domain knowledge.
        
       | derefr wrote:
       | > SIP was initially released in 1999, and was designed with the
       | assumption that each device has its own globally routable public
       | IP address. After all, the IPv6 standard was released back in
       | 1995, and NAT would soon be a thing of the past...right?
       | Unforunately, this did not end up being the case.
       | 
       | AFAIK, most residential _and_ commercial ISPs these days do
       | assign customers both a dynamically-DHCP-leased IPv4 _address_ ,
       | and a _static_ , globally-routable IPv6 _prefix_ -- usually a
       | /64, though some are nicer than that. If you put your ISP's
       | gateway router into bridge mode, and then plugged your computer
       | directly into it -- then your device would acquire both an IPv4
       | and an IPv6 address.
       | 
       | But routers -- including ISP gateway routers -- insist on doing
       | NAT not only for IPv4, but also for IPv6 (using the fe80::
       | prefix.) So on any regular home or office network, devices are
       | going to acquire private-use IPv4 _and_ IPv6 addresses.
       | 
       | Is there some reason that modern routers don't do NAT for IPv4,
       | while just further splitting+assigning the received prefix for
       | IPv6, such that every device on the network receives a private
       | IPv4 addr, but a _public_ IPv6 prefix, e.g. a  /72?
       | 
       | I know that Internet-backbone network switches ignore the last 64
       | bits of IPv6 in their routing tables; but those bits are still
       | being _carried_ in the IPv6 packets, and once they reach your
       | home router, _it_ can make use of them to route to the final
       | destination (i.e. one of the devices behind it.) Wasn 't this
       | supposed to be the idea?
        
         | t0mas88 wrote:
         | My quite basic free router from my ISP does exactly that. It
         | plugs into the UTP port on the fiber termination box (no idea
         | how to call that) and handles DHCP for ipv4, while allowing
         | ipv6 auto configuration using a /64 for all devices behind.
         | Seems to work out of the box for both Windows and Apple
         | devices. Only thing is that it automatically firewalls all
         | incoming connections on both v4 and v6, but I think that's a
         | very good default for an ISP device for home use. Especially
         | since everyone is so used to v4 being NATed.
        
         | kevincox wrote:
         | A lot of people expect a stateful firewall blocking incoming
         | connections on their local network. Applying the same NAT
         | system that is used for IPv4 to IPv6 is probably the best way
         | to get this layer of security.
         | 
         | Now in theory most devices should be safe to connect to the
         | internet. But how many Internet of Shit devices are there in
         | the average household that probably shouldn't be trusted?
         | Crappy security cameras with 10 year old firmware written by
         | the lowest bidder as well as "smart" thermostats that probably
         | aren't much better.
         | 
         | So maybe keeping the stateful firewall by default is the best
         | option.
        
           | jeroenhd wrote:
           | > A lot of people expect a stateful firewall blocking
           | incoming connections on their local network.
           | 
           | Totally! That's why that's the default setting for almost
           | every router out there.
           | 
           | > Applying the same NAT system that is used for IPv4 to IPv6
           | is probably the best way to get this layer of security.
           | 
           | No? The default firewall rules will work just fine.
           | 
           | > So maybe keeping the stateful firewall by default is the
           | best option.
           | 
           | Agreed. That's why routers ship with fully-closed firewalls
           | for both IPv4 and IPv6. Incoming connections need firewall
           | exceptions, either manually or through UPnP depending on how
           | you've configured your network.
           | 
           | In fact, because of NAT issues like NAT slipstreaming, an
           | IPv6 firewall is even more closed off than any IPv4 firewall
           | that needs to let through FTP(S), SIP, and many other
           | protocols depending on both sides of the connection using
           | IPv4 as designed.
        
           | derefr wrote:
           | > Applying the same NAT system that is used for IPv4 to IPv6
           | is probably the best way to get this layer of security.
           | 
           | ...why? Routers have (stateful) firewalls, entirely separate
           | from their NAT-ing abilities. You can still have the firewall
           | without the NAT. (And the protocols that IoT devices rely on,
           | like UPnP, are technically protocols for manipulating
           | _firewall rules_ , not NAT port-forwarding rules; so they
           | still work fine without NAT in place.)
           | 
           | > But how many Internet of Shit devices are there in the
           | average household that probably shouldn't be trusted?
           | 
           | I'm not sure about IPv4, but in IPv6 a given single logical
           | interface can acquire multiple IPv6 addresses -- meaning that
           | your laptop or phone will have _both_ a public global IPv6
           | address, _and_ a link-local fe80:: IPv6 address. And things
           | like multicast, DHCP discovery, etc. will only be attempted
           | or accepted through that link-local address.
           | 
           | Now imagine a router that combines that firewall rule, with a
           | bit of logic to automatically assign devices that join the
           | AP, to separate VLANs, depending on their MAC address vendor
           | part. So laptops and phones go on the "home" VLAN, while IoT
           | devices go on the "sandboxed" VLAN. Where these VLANs are
           | peered, but with stateful firewall rules between them:
           | "sandboxed" devices don't get to speak to "home" devices,
           | unless the "home" device speaks to them first; and multicast
           | packets from "home" devices won't reach "sandboxed" devices.
           | 
           | In other words, a home-network gateway-router should have all
           | the same defaults that an IaaS-tenant VPC does: nodes on the
           | network have public-routable IPs; but all inbound ports to
           | them are closed unless a device asks; and traffic flowing
           | between those devices can only be seen by other devices
           | intentionally put into that same VLAN, not by other "tenants"
           | who happen to be sharing the same pipes.
        
         | mgbmtl wrote:
         | > But routers -- including ISP gateway routers -- insist on
         | doing NAT not only for IPv4, but also for IPv6 (using the
         | fe80:: prefix.) So on any regular home or office network,
         | devices are going to acquire private-use IPv4 and IPv6
         | addresses.
         | 
         | Maybe I'm misunderstanding your comment, but fe80:: is a link-
         | local address and used by devices to talk to each other on the
         | network. It's there by default when IPv6 is enabled.
         | 
         | Most ISPs that support IPv6 will provide a /56 to the router,
         | and then the router will assign a /64 to wifi. Then the clients
         | get an IPv6 address using DHCPv6 or a route announcement.
         | 
         | Unfortunately most VoIP providers do not support IPv6. voip.ms,
         | which I use, for example, does not.
         | 
         | In my Asterisk pjsip configuration, I use:
         | 
         | external_media_address = dyn.example.org
         | external_signaling_address = dyn.example.org
         | 
         | where dyn.example.org is a dyndns that I use that points to my
         | home Asterisk server, on a dynamic IPv4 address. My ISP does
         | change my IPv4 address rather often, and sometimes I have to
         | restart asterisk for the change to be effective.
        
       | supertrope wrote:
       | You can install Acrobits Groundwire or Bria. Those support PUSH
       | notification for incoming calls. Push is better than missing
       | calls because the app got killed, or forcing the app to run 24/7
       | and severely shortening battery runtime. But the call quality
       | will never be as good as the native phone app as that gets QCI
       | prioritization.
        
       | Taniwha wrote:
       | I put in an asterix system 20 years ago, it still runs great, all
       | I've done has been to replace a couple of dying (RAIDed) drives.
       | I live in NZ used to live in the Bay Area, NZ trunks come in from
       | a local SIP provider and use an Ooma box for our old US phone
       | number, in home we had 5 FXSs and a sip phone in my office -
       | everyone had a phone in their bedroom, and a couple on public
       | spaces.
       | 
       | It's set up so that all incoming calls hit a voice prompt saying
       | which 1-digit extension you should enter to get who (this stops
       | 99% of phone spam) - everyone gets a voicemail on their extension
       | which rings in their bedroom and rolls over to the common spaces
       | - and everyone gets a unique ring cadence, my daughter who at one
       | point got 80% of the phone calls got the 2 short rings.
       | 
       | The kids have gone, we've moved to a smaller house, only 2
       | extensions, but that same hardware soldiers on (and still stops
       | 99% of the spam - I've had 1 call in the past year)
        
       | francescovv wrote:
       | Excellent article, and sections "NAT Problems" and "NAT
       | Solutions" are a good starter on that topic.
       | 
       | Except even third-choice solution is not always feasible.
       | Reserving fixed RTP/UDP port range is not possible with carrier-
       | grade NAT, which is quite common with residential ISPs and
       | nearly-universal with cell ISPs.
       | 
       | Fourth-choice would be to reserve port range on a personal server
       | (which would run B2BUA, asterisk in OP's case; or an RTP proxy),
       | and force calls, including media, from/to SIP handsets to go via
       | that.
        
         | astrobe_ wrote:
         | One often sees the STUN, TURN or ICE protocols around SIP-based
         | VoIP, I believed they were supposed to help solve those issues?
        
           | numpad0 wrote:
           | They don't always work...
           | 
           | The idea is if you send UDP packets to destination so
           | arranged by middleman(STUN) or to a proxy so arranged by
           | middleman(TURN) as an outgoing traffic, your Wi-Fi should be
           | smart enough to set up a temporary NAT entry to allow
           | responses to reach your $LOCAL_IP:$PORT. In reality, the Wi-
           | Fi may have short memory or may be dying behind a
           | refrigerator covered in dust and not able to handle all
           | necessary combinations and ranges of addresses and ports,
           | resulting in various partial failures such as one-way audio
           | or missing participant in a group call.
           | 
           | Fifth-choice option is to just encapsulate everything into a
           | VPN, preferably L2 VPN over HTTPS to a server on a global IP.
           | If it isn't working, there must be no Internet.
        
             | remram wrote:
             | Why would that be more reliable than TURN? If your router
             | "forgets" about established streams half-way, your VPN will
             | not stay connected either.
        
               | astrobe_ wrote:
               | UDP is unreliable transport _by specification_ , so I
               | guess that if a network equipment such as a router cannot
               | cope with the general workload, it would probably
               | sacrifice UDP first without a second thought.
        
               | remram wrote:
               | If you don't have any evidence, guessing that
               | routers/modems prioritize IP packets based on the next
               | protocol sounds like a conspiracy theory.
        
               | astrobe_ wrote:
               | Huh? It's an obvious thing to do. If you have to drop a
               | packet because your queues are full, any engineer with an
               | IQ over 50 will pick the victim from the UDP packets,
               | because the sender expects it might happen, and also
               | because it won't necessary cause a retransmission - e.g.
               | an RTP packet.
        
               | numpad0 wrote:
               | Makes it boolean. It's connected, or it's not. "One of
               | RTP media transports to one of destinations is failing to
               | establish DTLS ciphering and I think it has to do with
               | either RTC issue or Chrome bug" is a self inflicted pain.
        
           | deno wrote:
           | Yes, Asterisk can poke holes in NAT on its own just fine. I
           | was surprised how pessimistic the article is on this. I have
           | systems running for months and years behind NAT with no
           | issue. You might have to disable direct media
           | (endpoint/disable_direct_media_on_nat).
           | 
           | Also, this is just uptime related tip not NAT, you must
           | explicitly set registration/max_retries to a huge number
           | otherwise Asterisk just gives up permanently at some point.
           | It's a really weird default.
        
             | singpolyma3 wrote:
             | Are you doing calls to/from other sip URIs that are also
             | behind NAT, or just using your trunk and internal
             | extensions?
        
               | deno wrote:
               | Trunk and internal, and I usually put all the phones in
               | their own VLAN w/o direct Internet access. I don't really
               | see a use for dialing arbitrary SIP URIs. If I need to
               | add a remote phone I'll just connect it directly with a
               | network tunnel.
        
         | jeroenhd wrote:
         | All of the NAT problems would instantly to away with IPv6, but
         | with adoption still at a meager 50% I suppose you'll need a PBX
         | of some kind to receive at least half the calls.
         | 
         | For those stuck behind CGNAT, there are guides online for how
         | to set up a VPN to a cheap VPS and forward all network traffic
         | to your network so you can have almost-real connectivity at
         | home. If you're content with 50mbps, you can even use Oracle's
         | Always Free tier.
        
       | z3t4 wrote:
       | VoIP used to be standard on phones, even mobile smartphones. So I
       | setup Asterisk so that family members could call each others as
       | long as they where on WIfi. Unfortunately VoIP is no longer a
       | built in standard so you need to download an app to use it.
       | Before you could just dail 1 and my phone would ring, dail 2 and
       | you would reach my wife.
        
       | lormayna wrote:
       | One of my first job, in 201, was to create a spam faxing machine
       | based on Asterisk. Once the initial setup was completed (T38 is a
       | bit tricky to tune), it was very effective, it sent more than one
       | milion of faxes every year.
        
         | forgotmypw17 wrote:
         | Thank you for sharing your experience. How do you feel about
         | it?
        
           | lormayna wrote:
           | I am not the only sharing his experience with Asterisk in
           | this thread. Why this criticism?
        
             | forgotmypw17 wrote:
             | I commented because you reminded me of a similar experience
             | I had.
        
       | cyberax wrote:
       | I have a VoIP system at home as well. I first used an RPi with
       | Asterisk, but later switched to a Yeastar box with FXS ports (to
       | connect a couple of Old School wired phones).
       | 
       | One thing that is making me REALLY MAD is that there are NO IPV6
       | TRUNK PROVIDERS in the US. Not a single one. At least none where
       | I can just enter my credit card and get a phone line.
       | 
       | Somehow, the protocol designed to restore the end-to-end
       | connectivity is not used for the poster child of end-to-end
       | connectivity.
        
       | hashstring wrote:
       | > Use a SIP Application Layer Gateway. This is a horrible feature
       | offered by some routers. Basically, it deep-packet-inspects your
       | SIP traffic, rewrites the headers, and creates port forwards on-
       | the-fly to make sure the inbound audio stream makes its way to
       | your device. SIP ALGs are a total hack and notoriously buggy.
       | 
       | Yes, these hacky ALG features also allowed internet users to
       | access internal IPs on arbitrary services (!); named "remote
       | arbitrary firewall pinhole control". The attack was published in
       | 2020 and named NAT slipstreaming [1].
       | 
       | [1] https://samy.pl/slipstream/
        
         | jasonjayr wrote:
         | This was on by default on a consumer router that was used at a
         | small office. Their VoIP phones would get phantom calls until I
         | discovered this and disabled it.
        
           | hashstring wrote:
           | Woah, good find. How did you actually find out that this was
           | happening? Network captures?
           | 
           | When was this approximately? I'm wondering how widespread
           | this (still) is.
        
             | jasonjayr wrote:
             | It would have been 2-3 years ago. I was getting reports of
             | phones ringing, but no audio, no calls record from the VoIP
             | server CDR (which all phones were configured to proxy
             | through) and when looking @ the system logs from the
             | phones, they were reporting nonsensical IP addresses, which
             | pointed to something at the edge of the network.
        
           | jeroenhd wrote:
           | I'm pretty sure you've solved a mystery I was confused by
           | years ago, back when I was doing tech support.
           | 
           | It wouldn't have mattered much because the router/modem
           | combos in use didn't have a switch for SIP ALG anyway, bit
           | it's good router finally know what could've caused the
           | phantom phone ringing.
        
       | agwa wrote:
       | Nice article. Is there a benefit to using a queue for incoming
       | calls instead of just dialing multiple extensions with the &
       | operator?
        
         | deno wrote:
         | You get some statistics for queues but also for example you
         | might want to only take one call at a time even if you can
         | answer from multiple. Also Asterisk queues make it very easy to
         | do things like 'there's N callers waiting' etc.
        
         | kamma4434 wrote:
         | A queue shines when it can distribute incoming calls based on
         | it knowing agent availability. (Shameless plug: the company I
         | work for does cloud reporting [1] for Asterisk and FreeSwitch
         | queues - that is then whitelabelled and sold by a lot of big
         | name telcos worldwide. Not sexy but effective!)
         | 
         | [1] https://www.queuemetrics.com
        
       | aftbit wrote:
       | I have been tinkering with a personal VoIP system in my spare
       | time over the last couple of months. At this point, I have
       | rescued the 3 lines of house wiring in my 1970s house and
       | connected them to Asterisk on a VM via a Cisco MC3810 and a Adit
       | 600 channel bank. This has involved messing with T1s which was a
       | childhood dream of mine. I have 12 phones connected to the
       | system, using my house wiring, a few point-to-point wires, and
       | some SIP VoIP phones over ethernet. In turn these connect to
       | Phreaknet, C*NET, and of course the normal PSTN via a pair of
       | different ITSPs. I now feel almost qualified to build an early
       | 2000s business voice phone system, for what very little that is
       | worth. More importantly, I have a rotary phone on my desk. ;)
        
       | sylware wrote:
       | There is SIP and XMPP, but they may be overconvoluted for what I
       | am trying to achieve. Namely, I am not aiming at internet
       | universality (no IPv4 sharing abomination built into the
       | protocols).
       | 
       | I am looking at a modular set of protocols built mainly for IPv6.
       | 
       | The base: the "telephone number" would be ipv6:port. "Ringing"
       | and video/audio streams setup would be done here. End to end
       | encrytion right from the start (only manual key exchange, zero
       | automatic, even before ringing).
       | 
       | On top, a "comfort protocol"(one level of indirection) for those
       | changing ipv6, but not "accutely roaming", namely changing ipv6
       | while in a video/audio call: a "DynDNS" but simpler, more a
       | "current IPv6:port of 'name' kind of thing", "address book with a
       | drop of dynamic", "name@server" and you get the current
       | ipv6:port. Unfortunately, it means "accounts" and real time
       | updates. Of course, "server" could be a local/dns/ipv6. I am
       | thinking zero password, only a public key.
       | 
       | For video/audio streams, I may not bother and go TCP. The main
       | constraint would be the timing information shared among
       | video/audio streams. No "internet weather" dynamic
       | reconfiguration.
       | 
       | I even consider going "horribly horrible" for internet: idiotic
       | binary based instead of text based protocols.
        
       | KaiserPro wrote:
       | my wife had a requirement: be able to have an intercom for the
       | house and shed. We used to have a baby monitor, but that was one
       | way, for one room. Now we need many more rooms to talk to each
       | other.
       | 
       | I looked at some intercoms on amazon/ebay, they are all RF and a
       | bit shit. I saw some wifi ones, but nothing cheap enough to take
       | a punt on. I did think about trying to make something with an
       | ESP32, but that would be too hard for me in the time.
       | 
       | So I bought 6 cisco 7962 sip phones for PS35 in total, and
       | installed freepbx.
       | 
       | It took a bit of effort to bring the tftp server online, and make
       | sure all the dhcp info was being passed on correctly. Once that
       | was complete, freepbx makes most things pretty simple.
       | 
       | Now, I have ethernet is most rooms, and a switch that can do PoE,
       | so this solution is for a niche of a niche
        
         | numpad0 wrote:
         | I actually run 7962g + FreePBX too, using sccp_manager and
         | phone-integrated SSL-VPN. It took more hair pulling and shady
         | patching than the SIP route, but now I can make intercom calls
         | over the Internet! That way I don't need a direct L1/L2 link
         | between "offices". Solves NAT problems too, because it's all
         | in-band signaling and media transport over single TCP
         | connection.
        
         | nicolaslem wrote:
         | I remember playing with an old device as a child at my
         | grandparents' place, it was similar to a walkie-talkie but
         | transmitting using the mains power instead of RF. It was
         | supposed to plugged to a socket and hanged on the wall. It was
         | made exactly for the use case you describe, as an intercom
         | between rooms. It even had a button to ring a bell in another
         | room.
        
           | hiatus wrote:
           | These still exist, you can buy them on Amazon. [1] I figured
           | these had to exist as I recently saw a device to make a lan
           | using mains circuits.
           | 
           | [1]: https://a.co/d/31rKR02
        
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