I have an issue where intermittently I am not receiving audio on incoming calls from a particular VoIP provider. When I analyse the pcap files, I see the RTP stream comes in and the stream is made up of 1200+ packets, but when I decode the stream there is no audio received from the SIP provider. This is the same across codecs and is not limited to one particular codec or caller. One thing that does remain the same though is this only ever happens with calls from customers that are using the same SIP trunk provider - but it is an intermittent issue.
My SIP provider is telling me this is a firewall issue on my side, but can that be the case? It is possible that my firewall is removing the audio from the RTP packets sporadically? I cannot see how this can be? Has anyone seen this before and is there any way I can determine what is going on here?
My SIP provider has requested I run a pcap from the WAN side but given my setup and the location of the PBX this is going to be a bit of a nightmare.
Thank you in advance.
asked 24 Feb '16, 10:44
edited 24 Feb '16, 11:09
It sounds weird for several reasons:
Can you publish a capture of the "silent" RTP? A whole call including the SIP messages would be better but I can imagine there may be a privacy issue.
answered 24 Feb '16, 11:02