Has anyone got pjsip's stock iLBC to work in iOS? One out of every 3 or so calls has a very consistent choppiness, sounding as if it's a processor or bandwidth issue. Calls that are fine stay fine throughout the entire call, and calls with bad audio stay the same through the call as well. It doesn't seem to be a processor issue, as both good and bad calls use about 50% cpu on an iPhone 3GS. It doesn't seem to be a bandwidth issue, as the bad calls sound exactly the same and happen with the same frequency over fast WiFi as they do over 3G. I've tried tweaking all settings I could get access to in both the codec parameters and pjsua's various config structs. I've tried sending re-invites after calls connect. On the average, there's no more packet loss or jitter on bad calls than on good calls. I can't reproduce the issue using any other codecs, so it does seem to be limited to iLBC. 3rd party apps (Acrobits) can also use iLBC fine on every call using our registrar and engine. Acrobits sends its SIP messages through a proxy, though there's no real difference (other than format) between the content of its messages and my client's. The RTP packets don't look significantly different either. One other clue is that it sounds as though the same percentage of calls start out with the robotic choppiness in Acrobits, but Acrobits seems to correct these calls within a second. Pcapping from the server side didn't seem to reveal anything significant, and I was unable to determine what Acrobits is doing differently. Has anyone had any success in resolving this?
