I have recently purchased a SIP phone account with a local vendor.
When I set up the SIP client (X-Lite or PortGo), I can get my PC client to ring a standard phone, but no voice is actually heard. The account seems fine, since they installed my number on their PCs and called me. So I assume that there is something wrong with the audio codecs.
I called support and got a print-screen of the codecs they use (g.711 alaw/ ulaw and ilbc). I downloaded ACE codecs pack with only 3 codecs (g.711 alaw/ ulaw, plus gsm) and hoped for the best. However nothing changed.
Now, I am not very familiar with codecs and stuff, so I have no idea if the codecs were installed properly. My guess is that they were not, since the mike, headset and SIP account seem fine.
I am attaching a print-screen with the codecs that can be use by PortGo, the free client recommended by my SIP provider. Alternatively, if you know a free PC SIF Softphone, that would be able to install itself the necessary codecs, let me know.