ISR 4300 17.3.5 SIP Trunk Flapping

[balukr]

We have a customer with SIP trunk between CUCM and ISR 4351 Gateway router connected with PRI's. There was no issues when they were running on 16.12.03s  but when we upgrade IOS on 4351 to 17.03.05 SIP trunk to CUCM started flapping and never stayed up. We rolled back to 16.x as it was a hospital and did not have time to troubleshoot much. I couldn't find any bugs on this when I searched but wanted to check anyone have faced this issue, CUCM version is 12.5.1.14900-63.

Thanks

[Roger Kallberg]

Are you using server group and SIP option ping? There is a known defect with that combination in a few versions that results in dial peer being down even if the target system is operational. My recommendation would be to use 17.6.4 instead as the version you did use is not very reliable and it has multiple problems with Smart Licensing, the most noticeable one is that it closes down the SIP stack if it does not get an acknowledgment within the stipulated time frame.

[TechLvr]

I agree with you Roger. I recently had to deal with the same type of issue on IOS  version 17.3.4a. The output of “show sip service” showed sip service was down. There was also an error message regarding Smart License Acknowledgment when we did a “show license status” command. 

We upgraded to version 17.6.3a and the issue was gone. No smart licenses. 

[Roger Kallberg]

@TechLvr We recently moved all our 120+ ISR4K voice gateways from the same version that you use to 17.6.4 because of a defect that created massive issues with RUM reporting in Smart Licensing, so I’d recommend you to also do the same. At least if your using Smart Licensing in combination with an on-prem SSM. If so the SSM needs to also be running the very latest version.

[balukr]

Sorry for the late response. I was working back to back nights for cut over.

Yes, we use Server group and option ping. And yes, we had smart licensing issue as well though commands were completely different we were able to register (I think!) but not able to see all the information visible on 16.x on 17.3.5. I did not check "sh sip service" definitely verify next time if we had similar issues. Do you mind sending the bug id if you have it ? if not no worries. Thank you so much. I will pass this to our planning and test team to review.