SIP based SRTST : IP Phone not registering back to CUCM after SRST fallback

[jaheshkhan]

I configured SIP based SRST. Its working fine when link is down and phones are getting registered to voice gateway. but when link comes back phones are not registering back to cucm.

Cucm version 10.5

IP Phones 8841

There are firewalls between sites on both sides.

What could be the reason??

[Gregory Brunn]

Have you attempted to upgrade the firmware on phones.

Also your CUCM version is out of support isn't it or close to it? Might be time for an upgrade?

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCut87780

[jaheshkhan]

Yes. Its in their plan . but not at the moment. so we can only think of workaround at this moment.

current firmware for 8841 is as follows:

App load ID : rootfs288xx.12-0-1-11
Boot load ID : sb2288xx.BE-01-010
Version : sip88xx.12-0-1-11

firmware for 7821 is as follows:

sip78xx.10-3-1-12

both are not re-registering back to CUCM after link UP

[Roger Kallberg]

How are your rules in the firewalls setup? Can you post some details?

[jaheshkhan]

sorry for the delay.

Client told me that both sides firewall rule SITEA to SITEB any any rule...

if there is firewall issue, in SRST reverting back what ports we need to check?

[Roger Kallberg]

If it truly is any any there is nothing to check. As you have the firewall there I would recommend you to check the logs if there is anything blocked.

[jaheshkhan]

Today I upgraded 8841 firmware to sip88xx.12-8-1-0201-486. but Still SRST is not reverting back to CUCM unless reboot the phone.

I clearly dont understand what ports i need to check in firewall for this issue. if so i can request client to check that.

[Gregory Brunn]

Get a pcap from CUCM and a PCAP from the switch where the phones are connected.

Check out the following normal pcaps and registration and see where your break down is....

https://community.cisco.com/t5/collaboration-voice-and-video/phone-registration-pcap-and-logs/ta-p/3188036

The phones should attempt to re-register when the ping is successful.