I was sent out to activate another station on an existing CX installation. The set is a Mitel labeled 4110 set, which I believe is the equivalent to Inter-Tel's 5120 series. Anyway, I'm trying to add this phone to what should be the 13th station port on the system. Ports 1-8 on the first module are cross-connected and ports 1-4 on the second one. I'm using the fifth one.

I get dial tone with a butt set on the first pair and data noise on the second pair, so I'm sure my cable and jacks are good. When the phone is connected, I get talk battery in the handset and the display is fully functional, but the phone doesn't work otherwise. Do I need to get into system programming via X20 to activate this port or is there more to it? I don't think it is programmed as "disconnected" since it should be returning a busy signal when going off-hook under those circumstances. Could it be a polarity issue? Any ideas?

Don't everyone answer at once! I'm posting back to convey that I found out what the problem was in case someone else encounters this scenario. After returning to the site, I determined that there was something about the white/blue pair that the system didn't like. I could get dial tone across it with a butt set with no problem, all of the usual continuity testing passed, but once a digital set was connected, the pair didn't work for audio. After moving to another pair, it worked fine.

What's odd is that I only had a three pair cable to work with and the third pair was being used for a fax. I put the fax on what was the "defective" white/blue pair and it works perfectly fine.