Quote:
Originally Posted by martin
We would be interested to know what the situation is when a different UAC is used other than the Atcom. Is there any chance that the above analysis could be reperformed with a different client?
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The only other SIP devices I have are softphones.
I tried with the X-Lite softphone, but the results were worse. After receiving the re-INVITE, the phone changes to sending the RTP packets direct to Pennytel, and it seems to work, but I get the occasional "ICMP port unavailable" error returned. If I force the X-Lite softphone to send a re-INVITE by putting the call on hold, then resuming, the incoming RTP voice packet stream remains unchanged, and every outgoing packet (direct to Pennytel) is rejected by Pennytel with "ICMP port unavailable". I end up with one-way audio and DTMF not working.
I'll post the SIP trace with commentary later.
Atcom AT-530 + VoXaLot + MNF works
I also tried doing the above test with the Atcom AT-530, but sending the call out via MNF instead of Pennytel. That worked as intended - after the call was answered, us.voxalot.com sent me a re-INVITE (with the SDP referring to MNF's RTP server), the AT-530 replied with 200, with an SDP referencing itself, us.voxalot.com ACKed that, and then straight away the RTP voice packets changed to going direct between me and MNF.
I noticed a small hiccup in the voice during the first half a second. (The number I was calling (an IVR service) answers with "Welcome to..." . The RTP stream was modified in the midst of the word "Welcome", so what I heard was "Wel'to..." (the "come " must have been in transit over the Pacific Ocean when the direct RTP stream arrived)).
That would seem to suggest that it's got something to do with Pennytel.
I also tried the above test with the Atcom AT-530, with Pennytel as before, but using PBXes instead of VoXaLot. The results were the same. PBXes successfully unproxied half of the voice stream (after sending me a re-INVITE), and then the other half was unproxied after I hit the "Hold" button twice.
I also tried:
Atcom AT-530 -> PBXes -> VoXaLot -> Pennytel
and the results were the same (haven't tried the reverse order though).