Via Expressway 12.5.7 Mobile Device Jabber is OK, but Windows Jabber can't Dial Out

[UrbanPeasant]

Hello,

Having deployed Xprswy 12.5.7 E and C clusters with our CUCM 10.5.2 infrastructure in a single domain, non-split DNS environment, when we hide the cisco-uds and cuplogin SRV records BOT and TCT Jabber clients can log in via Xprswy and seem to work fine: can make and receive calls, presence, contacts, voicemail.

Windows and Mac clients can alos appear OK at first glance but cannot make calls.

When they dial out there is only silence before eventually fast busy. 

Troubleshooting this is problematic because I have to get a different team to hide the SRV records (5 min TTL) havea quick go at VPNless connectivity, then make the SRV visible again because people quickly start to query why Jabber isn't working as they expect!

The collaboration tester at cway.cisco.com shows info that only says it failed to retrieve the device's config from TFTP - but that can't be right because my CSF managed to log in and can receive calls. Or have I missed something there?

Often as I sit to type out a question for the community I come to an answer by clarifying my thinking as I lay out my problem, but this time, I'm plain stuck. I can't figure why BOT/TCT works and CSF seems to work in all respects EXCEPT it can't dial out. So I have to fall back to the VPN model.

Can anyone suggest things that I should look into

Thanks

Nathan

[UrbanPeasant · Accepted solution]

Took a long while to get to the bottom of this and eventually involved TAC.

The problem was that the CSF client was sending a frame that was bigger than the maximum size specified in CUCM Service Parameters Advanced Settings - Device SIP - SIP Max Incoming Message Size.

The maximum was set to default of 5000 bytes, the recommended value in CUCM is 11000 bytes. We were sending a frame of 5453 bytes. With fewer SDP service capabilities the BOT and TCT clients must have been sending smaller INVITE frames in, and so not hitting the limitation.

For the failing calls on the Expressways logs, the pcap shows the INVITE going out from the Xprswy Control to the subscriber with 5453 bytes, and the corresponding SDL trace from CUCM displayed message:

"AppInfo |SIPTcp - Ignoring large message from <subscriber-IP>:[26066]. Only allow up to 5000 bytes. Resetting connection."

This resulted in the reorder tone after about 20 secs.

I've updated our frame size to 7000 now, and we can now make VPNless Jabber outbound calls from CSF devices (Win/Mac).

There's a similar problem here, with detail on how to drill down to adjust the value: Doc ID 118345
https://www.cisco.com/c/en/us/support/docs/conferencing/telepresence-server/118345-probsol-telepresence-00.html

SIP Message Size Restriction Causes Calls to Drop

Kind regards to all

Nathan.