We have a 2811 router running 12.4.11T4 with an VIC-4FXS/DID module. The router is an MGCP gateway with CallManager 6.0.1.
When calling the analog devices on the FXS ports with an IP phone, the IP phone says "connected" but you keep getting ring back. Calling from the PSTN just gets ringback.
We've switched out the module with another and same result. Outbound calls work fine...just inbound calls never fully connect.