I have the following configuration.
PRI->2851 Gateway-CAS T1->Nortel PBX->Modem
There are no T1 problems between the Cisco and Nortel devices (no slips, etc) but modem/fax connections are slow and unreliable. Voice works perfectly.
I have some modem passthru commands on the MGCP gateway to support ATA186s that I have in service for fax machines, (they work well) but I am wondering if I need any additional commands for the Nortel device?
Here is my MGCP config as it stands:
mgcp call-agent CALLMANAGER-1 2427 service-type mgcp version 0.1
mgcp dtmf-relay voip codec all mode out-of-band
mgcp rtp unreachable timeout 1000 action notify
mgcp modem passthrough voip mode nse
mgcp quarantine mode process loop
mgcp package-capability rtp-package
no mgcp package-capability res-package
mgcp package-capability sst-package
no mgcp package-capability fxr-package
mgcp package-capability pre-package
no mgcp timer receive-rtcp
mgcp sdp simple
mgcp fax t38 inhibit
mgcp rtp payload-type g726r16 static
mgcp profile default