[tacticalogic]

Agreed, though in the worst case, dropping to a PSTN interface and transferring the call to another system’s PSTN interface might work. Cumbersome though.

And it has to work in both directions. The mail server has to accept incoming calls and save the voice mail messages as audio files, and be able to initiate an outbound call to play back the message on your phone if you want.

[taxcontrol]

Exactly right. Which is why POTS interfaces make the poorest possible option.