testing dial up modem over VoIP

NO.

So IP telephony systems do support modems, but they dont use an IP phone - the speech compression system tends to scramble the signal.

If you had a phone set to do G.711 (which is 64k of data, maybe 80k or more with overhead) you may get somewhere, since that is the same digitisation used in a conventional TDM pbx - and your modem has to work with that....

You can't use a conventional dial-up modem over any compressed VOIP line and even G.711 uncompressed is going to be a challenge unless you've got voice priority (802.1p/q) working end-to-end.

I couldn't even get a modem to work thru a Sipura 3000 going from the POTS port out the PSTN port. This is implimented in the Sipura as a VOIP connection between the two ports inside the box.

I've completely given up on being able to connect modems via VOIP.

Mike Schumann

Yes it is possible, but the tricky part is keeping the voIP conenction solid enough. Be sure that you are running g711u law and not g729. That is the first point to start.

Well there is also X-lite iLBC ..

oh and don't forget GSM

WHat I do not get is why there does not seem to be any hardware phones that support them .. beyond professional office phones like Snom..

(not snom supports GSM but no iLBC yet anyway)

Anyone know phones that support these two standard codec's .. I figure since snom is based on linux and is pretty much a open phone that they will support it before the otheres..

m.