IP Phone loses registration when called from another IP phone

[msaltissi]

Hi, I have an issue that I could really use some help with please.

When another IP Phone 7821 calls my 8941, my phone loses registration and says on screen "Phone not registered" for a few moments.

It seems to mostly be happening on 89XX models that lose registration.  Other users are reporting the same issue to me.

I can reproduce the issue but I need some advice on how to diagnose it.

The phone status messages don't really tell me much.  I only see "Error VPN is not configured" and "CTLSEP5057A887AC27.tlv not found" but from what I have read this is normal operation when not enforcing certificates.

Many thanks! Mark

[msaltissi]

I enabled port spanning on my phone.  After my phone restarted the first test call worked, but the second failed.  I collected the traces from both calls so I have that for comparison.

I can see TCP re-transmissions from my phone during the failed call.  During a failed call it stops at '100 Trying' and does not get to '180 Ringing' on my phone. 

Please see attached. My phones IP is .48 and the CUCM is .51.

Capture 1 is the failed call and Capture 2 is the working call.

I'm looking into the re-transmission now.  I thought a re-transmission would occur after a SYN is sent and no ACK is received.  It does not look to be the case here because there is no original SYN that I can see from .48.

[Manish Gogna]

SIP signaling wise it is okay, it appears to be a network related issue to me. I would suggest posting it on the switching forum with the show tech from the switch as well as the complete packet captures from the affected phone for a test call that triggers reset.

Manish

[Manish Gogna]

Hi Mark,

What are the cucm and phone firmware versions involved?

Does the issue happen only when 78XX phone calls an 89XX phone?

Are the calls involving only 78XX or 89XX phones working fine?

Have you tried a call between a 78XX and 89XX that are in the same device pool and connected to the same switch and still faced the same issue?

Detailed callmanager service traces and preferably a packet capture from the affected 89XX would be needed to diagnose further.

HTH

Manish

[msaltissi]

Thanks for your reply!

What are the cucm and phone firmware versions involved? CUCM version 10.5.1.10000-7, CP-8941 has sip 9-4-2-sr3-1 and CP-7821 has sip78xx.11-5-1SR1-1

Does the issue happen only when 78XX phone calls an 89XX phone? I have tested from three 78XX but only two of them trigger the restart.  I have only tested from one other 89XX and it does not trigger the problem.

Are the calls involving only 78XX or 89XX phones working fine?  I have not had a chance to test fully.  I just then made one test call between two 78XX and it was fine.  Also, I have not heard of any issues from other users with 78XX phones calling between them.  I have made several tests between two 89XX and not found any issue.  I can test with more tomorrow.

Have you tried a call between a 78XX and 89XX that are in the same device pool and connected to the same switch and still faced the same issue? All my tests at the moment are within the same pool and switch and I experience the issue.  I have had reports from senior management in other office in different pools with 89XX phones to have experienced the same issues I can reproduce here.

Detailed callmanager service traces and preferably a packet capture from the affected 89XX would be needed to diagnose further.  I just posted a screenshot of a trace before I noticed your message.  Maybe that can give you an idea.  Can you please advise how I can collect the detailed callmanager service trace?