Hi, I have an issue with Callmanager 6.1 and 7942`s and 7945`s using SRST version 3.3 on a 2801 router.
The phones fall back into SRST mode, but the phones lose their extension numbers, so are unable to make and receive calls.
From the compatibility docs, Cisco produce it would appear that version 3.3 does not support these phone models.
Does this mean a complete IOS upgrade to get the updated SRST or can you download some kind of component?
Hope you can help.
For IP Phone support in SRST for the 7942 and 7945 you will require at least SRST version 4.1.
Refer the SRST 4.1 Product Reference Guide:-
In particular, please refer to Table 7 of this document, it details which SRST version is available with a specific release of IOS. In your case v4.1 is available for release 12.4(14)T.
You may also find this document helpful, is various FAQs about SRST:-
Hope this helps