Is there a setting in the TSU 120 to select NI-2 or Custom? I'm switching phone service vendors and right now everything is working when connected to vendor 1's smart jack. If I switch the connection to vendor 2's smart jack, everything seems to sync up, there are no alarm or error lights but the phones don't work; no dial tone. Connections are Smart Jack --> TSU 120 --> Comdial DXP. I know the coding and framing are set correctly but the PRI type is the only thing I'm not sure about. Vendor 2 says they have the type set to "Custom".
The TSU 120 does not have any PRI switch type settings, as it is transparent to the PRI. The PRI switch type would have to be configured in the Comdial DXP since it is what is terminating the D-channel.
The TSU 120 will need the correct channels mapped to the DSX-1 port, but it is strictly pass-through.