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New Member

7961 phones stuck in SRST fallback with WAN link up??

CCM 4.23 SR2b, 7961 FW version is SCCP41.8-2-2SR1S. H323 gateway 12.4(8c). Some phones mysteriously get stuck in CCM fallback SRST mode and do not re-register with CCM even though WAN is up. Only thing that gets the phones back is to cut the power then they register back to CCM fine??

config excerpts:


interface Loopback0

ip address

no ip redirects

no ip unreachables

no ip proxy-arp

ip pim sparse-dense-mode

h323-gateway voip interface

h323-gateway voip bind srcaddr


max-conferences 8 gain -6

ip source-address port 2000

max-ephones 42

max-dn 30

voicemail 95556587

alias 1 3200 to 7500


multicast moh 239.x.x.118 port 16384 route

Before I go into debug/trace mode I wanted to check if anyone has seen this??

Thanks in advance,


New Member

Re: 7961 phones stuck in SRST fallback with WAN link up??


Can you check the CallManager list in the Device configuration in the settings button of the phone? Somehow the phone can't reach the CCM ip addresses list in this list.

From your CCM, can you ping this phone's IP address? Try a constant ping. Any drops?

Lastly, is there any firewall btw?

Just my two cents.


New Member

Re: 7961 phones stuck in SRST fallback with WAN link up??


Yes, we have started to see this. We have over 2000 IP phones spreadout over a dozen or so branches with a centralized CallManager cluster at the Data Centre. When the Data Centre WAN link goes all phones go in SRST. When the WAN link is restored, quite a few phone remain in "CM fallback" mode. I used a sniffer on one of the IP Phones which was stuck in SRST and I did not see it sending the 120 second keepalive/retry to the the CallManager subscriber (as it should be according to Cisco SRST documentation "Cisco SRST V3.2: Overview of Cisco IOS SRST"); I only see the 30 second keepalives to the SRST router (and the response from the router).

Resetting the Phone fixes it, or you can go to the SRST router and type:

conf t


reset all

Our SRST config looks just like yours.

We are using CallManager 4.2(1) and skinny client Firmware SCCP41.8-2-1S. All IP Phones are 7941G, with some 7911's and 7961G's.

I'm currently looking through Cisco bug lists but haven't found any known bugs with this skinny client firmware that fits this problem.

I will try upgrading all skinny client software on IP phones before loggin a TAC case.