I have a strange issue happening with one of the phones at the company I work for. Hold music starts playing on some calls about 15 minutes into the conversation. The callee hears the music but not the caller, and voice communication is severed. It's only been happening over the past two weeks, with no configuration changes to the PBX during that time. We're running Incredible PBX 13-12 (FreePBX).
So I did a tcpdump and analyzed the packets in Wireshark. Here are the flow sequences.
[att=1]
between PBX and SIP provider
[att=2]
between Phone and PBX
Could anyone shed some light on what's going on? It looks as though a re-invite from the SIP provider is disconnecting the call, leading to the hold music.
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