I had recently a strange problem in ISDN.
A C2600 router, that has a microwave link as primary and ISDN as Backup interface, is working very fine.
When upgrading the same configuration to new router C2811, the BRI interface is always UP, when i debugged the dialer, i found that traffic is being sent from the BRI interface sourve to 188.8.131.52(eigrp multicast),
Jul 25 23:06:35 : BR0/0/0 DDR: place call
Jul 25 23:06:35 : BR0/0/0 DDR: Dialing cause ip (s=172.17.1.18, d=184.108.40.206)
Jul 25 23:06:35 : BR0/0/0 DDR: Attempting to dial 01966115
Jul 25 23:06:36 : %LINK-3-UPDOWN: Interface BRI0/0/0:2, changed state to up
Jul 25 23:06:36 : %ISDN-6-CONNECT: Interface BRI0/0/0:2 is now connected to 019
So how could applying exactly the same config on 2 different routers, create such a difference???