I have a customer with a unique situation. Currently he has 2 lines with Viatalk. The lines come into his office where they convert to analog as he only has a few 2 line phones.
What he would like me to do is hook up an Allworx phone system in his office because of the need soon to have a couple of remote phones in another town.
My question is, has anyone tried to put an Allworx (or a TDM system for that matter) behind Viatalk lines? I'm wondering about their disconnect, audio quality, etc.

I can't answer your question but will pose another. Could you just have them allow SIP login direct from the Allworx? It would probably be better.

At this point in time no. Going forward, as their business grows and they have to find another carrier other than viatalk, then sure, that's the way to go.