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CVP survivability tcl

Did anybody have success in deploying CVP survivability tcl script?

I tried to follow CVP 3.1 SRND, the call can not be transferred to an IP phone. The testing scenario is, if the call sent to CVP/ICM doesn't get label, the cvp survivability tcl takes over, and send call to pre-defined DN. If this number is for PSTN, it is fine, however if it points to CCM/IP phone, it fails. I can see the dial-peer is triggered, but it goes nowhere.

The voice gateway is 2851 and IOS is 12.4(3b) ip voice, which is recommended in CVP 3.1 Bill of Materials.

Any ideas?


Community Member

Re: CVP survivability tcl

Hi Wei,

This was a known IOS bug CSCsb73574 that has been fixed in 12.4(7b) (which is now officially qualified with CVP). If you load that IOS version, the CCm transfer will work.



Re: CVP survivability tcl

Janet, we are running CVP 3.1 SR1 and 12.4(3c) but have run into a bug:


Externally found moderate defect: Resolved (R)

SRST does not Unregisters E164 number from Gatekeeper when CCM comes up

Release Notes:


When CCM is available again and IP Phone unregisteres from SRST, the SRST router does not unregisters the E164 number from Gatekeeper.


They are running 2821/2851's. What is the best tested IOS to be at right now? 12.4(3d) and 12.4(3e) have a bad DSP bug so prefer to stay away from those.

Community Member

Re: CVP survivability tcl


Nice to see you have your CCIE Voice. Well done :)

This is a defect that I had found in my current deployment. Current news is it is fixed in 12.4(7c) due out soon........

A workaround I have used is to reply with labels that are prefixed with a digit. Then use Call manager to do a translation to the real numbers. This way the unregistered numbers do not effect you. A not elegant workaround but it works.

Please rate the post .....


Community Member

Re: CVP survivability tcl


Thanks for the information. I loaded IOS 12.4(7b) into gateway, it still doesn't work, the symptom becomes, the ip phone can be rung, however, when picked up, the call is not connected, returned 'fast busy' tone. It seems the signaling path is established, but rtp is not.


Community Member

Re: CVP survivability tcl

Yes, IOS 12.4(7b) does fix the problem in AS5400XM, but not in 2851.


Community Member

Re: CVP survivability tcl

This H323 code is the same for all the platforms (5x, 3x, 2x gateways).

1. Turn on "debug h225 asn1" on the 2851 (only turn on off-hours since it is very verbose) and make sure you see the H225 setup message going out to CCM with a guid that does not contain all zeroes. If it looks like a valid guid, then the bug is fixed.

2. Does the phone ring? If it does and then drops, it is a different issue and sounds more like a codec incompatibility. What codec does the phone support when talking to the gateway?

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