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New Member

Upgrade to IOS 15 broke SRST

I upgraded a 2801 router from 12.4(24)T6 to 15.1(3)T2 and SCCP SRST stopped working (I've also tried 15.1(4)M2). It works fine on 12.4, but with 15.1, the phones never register. Debug ephone detail produces no output at all. The config is pretty basic.


max-conferences 4 gain -6

transfer-system full-consult

ip source-address port 2000

max-ephones 6

max-dn 8

time-zone 12

Am I missing something? I know on a 2900 platform I need to add a license, but I was told by TAC that on the 2800 I do not. Is that incorrect?

Everyone's tags (2)

Upgrade to IOS 15 broke SRST


TAC are right you dont need a license for ISR-g1 like 28xx

After moving to ver 15.1.2T

Cisco have brought in IP trusting for voice gateways

As you have upgraded to 15.1.3 you will need to either configure and fix your

IP trust lists or turn off the feature

Can you post the output of

show ip address trusted list

I am enclosing the URL which explais this "feature"



Regards, Alex. Please rate useful posts.
New Member

Upgrade to IOS 15 broke SRST

Thanks for the response Alex. I already turned the trust list off with "no ip address trusted authenticate" but it didn't make any difference. I thought that only affected SIP and H.323 connections. The problem is the phones never register. Surprisingly, SIP phones work fine even without the trust list turned off. It's only SCCP phones that don't register.


Upgrade to IOS 15 broke SRST


Sorry I have not looked at this post for a while.

May be you have already solved the issue.

I have tried searching for bugs but did not find much re your kind of issue.

Can you try

debug ephone raw

This is supposed show all the low level sccp messaging



Regards, Alex. Please rate useful posts.
Cisco Employee

Re: Upgrade to IOS 15 broke SRST


If possible please send this show command.

show tcp brief all


Re: Upgrade to IOS 15 broke SRST

I believe this is due to the fact that SRST now has EULA that will have to be accepted before it will work. The command will be 'license accept end user agreement'.

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