Jabber drops audio one way

[ZenraiBaishuu]

We're having a very sporadic issue where, when clients connected remotely to Citrix Gateway VPN, Jabber calls drop after a minute and a half or so but only one way. One user will be able to hear the other but not vice versa. Jabber version is 12.9.3 any help or ideas would be great as it's not happening with everyone and for some users it's happening regardless of which machine they take home. Obviously this has led me to think it's their home internet but what would make it stop working after a time period versus just not at all and why only one way? 

[OnkarMahajan38629]

Hi ZenraiBaishuu,

Generally, call drop or audio drop during the active call happens if SIP Reinvites/Updates fail during the call. E.g. When the call was first connected, SIP dialog from Invite to 200Ok was successful, after some time (in your case around 90 sec) one of the party initiated media renegotiation but that failed, it could be for any reason like media parameters were changed, SIP packet size was bigger than previous and hence it was blocked by network device etc.

I would start with narrowing down the issue - Is it happening only for Jabber and not physical phones?, Only Jabber over VPN and not Jabber from corporate network?

If happening only for Jabber over VPN then more chances that VPN GW (or VPN network path) is causing reinvite SIP dialog to fail.

If happening for both Jabber over VPN and corporate network then more chances that either CUCM or PSTN doesn't like new media parameter's introduced during the reinvite.

Wireshark packet capture from Jabber client, PSTN GW and CUCM traces would tell the exact reason.