Call drops when receiver of call resumes from hold

[j...@ffej.net]

Hi Everyone,

I have recently moved a functioning sipXcom installation to a new server with the backup / restore functions in the web interface.

Everything seems to have copied correctly, however since the move I'm having issues resuming calls from hold.  

If the party who made the call places the call on hold everything works well, but if the party receiving the call places it on hold there is no hold music received and the call drops out on resume.

For example:

Working - Caller places call on hold:

1) Phone A (2111 - 10.1.100.2) calls Phone B (2113 - 10.1.100.3)

2) Phone B answers call from Phone A successfully, 2-way audio.

3) Phone A places call on hold, Phone B receives hold music.

4) Phone A successfully resumes call from hold, hold music stops on Phone B and 2-way audio resumes properly.

5) Phone A ends call.

Packet capture here - https://drive.google.com/file/d/1iXhs0wZXkX2n_5Jj1jyeXfOPI9P0oDTW/view?usp=sharing

Not Working - Receiver places call on hold:

1) Phone A (2111 - 10.1.100.2) calls Phone B (2113 - 10.1.100.3)

2) Phone B answers call from Phone A successfully, 2-way audio.

3) Phone B places call on hold, Phone A is silent, no hold music.

4) Phone B attempts to resume call from hold, call does not resume, no audio between phones.

5) Call either disconnects after approximately 30s with fast busy on Phone B, or hangs forever with no audio.

Packet capture here - https://drive.google.com/file/d/179hUXhv4yZgaCe_hbnZxrCqyKJrou-4J/view?usp=sharing

The failing packet capture shows the invite from Phone B (10.1.100.3) via sipxcom (10.254.20.10) to Phone A (10.1.100.2) to initiate the hold music transaction retries five times before failing with a "482 Loop Detected" error. 

During the server swap, the internal IP and external IP addresses were changed.  My gut feeling is DNS, but the web interface DNS advisor states "DNS Configurations is valid", so not really sure.  

The previous server was running 18.04, new server was installed using 18.08 and transfer was done to this version (which showed the issue).  I have since upgraded to 18.12, but the problem remains.

Polycom UC firmware versions is 4.0.12.0926 on both devices, this hasn't been updated since before the server change.

Can anyone shed some light?

Thanks for your help.

Jeff.

[pmkr...@gmail.com]

Check packet 33 of the problem PCAP and compare with packet 38 of the good pcap. When x2113 (receiving call) is placed on hold, that phone should return an invite of ~~mh~u2...@sinope.voip.cornick.com.au to Sipxcom - this field is found in the 2113 line-> registrations->musiconhold.uri field of the phone. Factory resetting the phone or deleting / reinserting the phone in Sipxcom are things to try.

Peter