i have a CUCM 6.1(2) with one 2811 router.
In this router (IOS c2800nm-ipvoice-mz.124-22.T5.bin) there are 2 PRI, 2 BRI configured with MGCP (one for PSTN and one for communicate with one PBX).
In general all works fine, but there is a problem: when i call one IP Phone through one of the two PRI or BRI (external call through direct number or call from PBX), if this Phone is unregistred, the Call Forward Unregistred doesn't work, but if i call this phone from another IP Phone it works.
It isn't a problem of CSS because if i put the same CSS in Call Forward All and i try to put the same call (through PRI or BRI) it works.
It seems like that the CUCM can't communicate the correct indication for Call Forward Unregistred through MGCP, and i hear fast busy. I have the same scenario with CUCM 7.0 and it works fine.
I've already change the IOS of the router without good news and i wouldn't upgrade the CUCM for the moment.
Here is the q931 output for CFU
001503: *May 22 10:45:21: ISDN Se0/0/0:15 Q931: TX -> CALL_PROC pd = 8 callref = 0x803A
Channel ID i = 0xA98385
Exclusive, Channel 5
001504: *May 22 10:45:21: ISDN Se0/0/0:15 Q931: TX -> FACILITY pd = 8 callref = 0x803A
Facility i = 0x91AA06800100820100A40702020BD5800100
001505: *May 22 10:45:21: ISDN Se0/0/0:15 Q931: TX -> DISCONNECT pd = 8 callref = 0x803A
Cause i = 0x81A9 - Temporary failure
Thanks a lot.