We currently have a 3640 with MICA Modem bank connected to the PSTN via T1 PRI for dial-in. That setup works well for both inbound and outbound dialup.
I have been asked, however, to move the T1 connection to our enterprise Cisco Callmanager system.
So, I have connected (via T1 crossover cable) the dial-in 3640 to one of our 3745 voice gateways. The T1 between them is running clean (no slips or linecode violations). The T1 port on the 3745 has been built as mgcp in Callmanager and is registered. I have also pointed a test DID route pattern to this gateway.
When I call into the DID number, it appears that the modems are trying to connect and that they are negotiating their speed downwards several times. Sometimes the modems connect, most often they get hung at the "verifying username and password" step. I have verified that we are using modem passthrough. There doesn't seem to be much other config, but I cannot get this to work reliably. Does anyone have any ideas or suggestions?
Any information is appreciated.