E1 or T1 conection to the PBX???
A sugestion: To test that your gateway is working O.K. when you do not have a T1 or E1 instrument, you could loop one port to the other.
Wit a little bit of programing on the DX, you could make a call come out on the T1 port, and come back in into the second one.
Always found that to be the best way to test the T1 or E1 ports on the gateways.