INT 14 - TelAPI - ???
        AH = ECh
        BX = ???
        CX:DX = ???
        DS:DI -> ???
        ES:SI -> ???
Return: AX = status (0000h,FF37h,etc.)
        ES:SI -> ??? if ???
        ???
Note:   this function is not supported by the Microdyne TelAPI v3.7
SeeAlso: AH=E0h"TelAPI",AX=FF00h

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