Expressway One-Way Audio Mid Call

[sean Riley]

I am having an issue with one way audio occurring mid call through our Expressway. Only inbound calls seem to be affected. Outbound calls do not experience this issue. Also, calls not using expressway do not experience this issue.

The called endpoint (inside phone) can not be heard. This happens a few seconds before the 15 minute mark of the call. Putting the call on hold and resuming restores 2-way audio and the issue does not occur again (test call up 30+ more minutes after resuming from hold).

This happens on both Jabber and 7800 Endpoints (this is all we have using expressway).

The 15 minute mark seems to be half of what our SIP session expire timer is set to in CUCM.

My hope is that this is a configuration issue on the gateway or expressways and will not require packet captures or traces.

Call Flow: Outside caller ==> PSTN ==> H323 gateway ==> CUCM ==> Expressway C ==> Expressway E ==> Cisco Jabber/7800 Endpoint connected over Internet.

The Expressway E is dual NIC in DMZ's on a Palo Alto Firewall. Expressway C sits in DMZ on the Palo Alto.

Expressway v 8.10.4
CUCM v 10.5(2) SU 3a
h323 gateway: ISR 4331 v 15.5(3)S7b

Thanks 

[jonathan.salter]

Interesting....I will have to look into this one.

I had phones that would go into preservation mode after 30mins.....never got to the bottom of it and they just stopped behaving like that one day out of the blue with no intervention from me.

I would certainly love to see at least the CUCM traces from a call.

[Wayne DeNardi]

Do you have SIP ALG turned off on your firewalls?

[sean Riley]

I have not disabled SIP ALG on the PA yet. I did come across some information pointing to this, but thought if this was the issue, it would not matter what direction the call was made from as to when the issue occurs.  

[sean Riley]

Just tested disabling SIP ALG on the firewall and still had the issue.

[Rafal Szeremeta]

Hi Sean,

Is this new set up or was working fine till now?

Thanks

Rafal

[sean Riley]

This is a new configuration as of May 2018.  As far as I know this issue has been there since we implemented.

[sean Riley · Accepted solution]

Cause of this issue was BugID CSCuw60623.  Increasing the SIP Session refresh interval on the Expressways to the max is a workaround until we can upgrade our CUCM to a fixed version.