The VOIP setup that I was using and tested ok with yesterday is not working, everything is answering but there is noise or bad latency on the connection causing drop outs.
I have moved the second line to a real phone line which is now accessible via...
Remember that this is designed to accept connections from old stuff and therefore does not do any error correction or auto negotiation it needs to be set to V23 7E1 and you need to turn off any clever features on your modem.
I'm using the following AT initialization string I'm using on the server side which works with the Terminatel ViewData terminal...
AT &F0 &C1 &D3 &R1 &S1 &K3 &Q6 B0 %C0 %E0 M0 Q1 E0 +MS=V23C,0
After trying this with a modern modem +MS=V23C,0 seems to be required to get it to connect, B0 &Q6 &K3 may all be required on your modem to dial in correctly.