I have a T1 PRI circuit from the local ILEC going to a PBX where there is no way for me to look at the interface for any errors. I was considering installing a NetVanta 3200 between the T1 and the PBX and then configuring the Eth 0/1 interface for remote access. The T1 is a straight PRI without any IP's as there is no data(only the D channel) What I am looking for is some help on the config, the NetVanta has the Module with the Wan-T1, DSX-1 and DBU connections. I believe with the correct config I can connect the WAN-T1 to the ILEC smart jack, the PBX to the DSX-1 and my existing internet to the Eth 0/1 port with a static IP from my DSL circuit to enable remote access.
The easiest thing to do here would be to monitor the PBX interface itself for errors. Inserting another piece of gear gives you another potential point of failure in series, or for temporary troubleshooting use test equipment such as a T-BERD.
If this isn't feasible, the best Adtran box to put in the loop would probably be the TA908e. It can terminate the PRI coming from telco and generate PRI to the PBX. You can manipulate parameters such as switch type and messaging, even peel off phone numbers to analog lines or SIP. I don't think the 3200 will properly terminate TDM voice.