I wanted to pass on a situation that we had never seen before with a Shortel client. The client had been successfully running a new Shortel system for about 6 months. After a bout of bad weather and problems with additional analog lines on site, the T1 trunk line servicing the Shortel 220T1A went down. In looking at wiring specs for the uplink from the T1 smartjack to the Shortel 220T1A, it was decided that perhaps the uplink cabling had gone bad and needed replaced. A brand new CAT5e patch cable new out of the packaging would not uplink the device. However, in trying various combinations of crossovers and other straight through cabling just to rule out that ATT had not changed something on their end, it was decided to try a CAT6 cable instead of CAT5e. After making a straight through CAT6 cable, the uplink fired off and everything came online. We have talked with various Shortel installers who have never seen this problem and could not believe the remedy. After using the CAT6 cable for a while, we decided to test to see whether or not the CAT5e cabling would work. After plugging the CAT5e cable back in, everything went down again. A completely separate new cable was used as well to rule out the possibility of a bad cable; same results. As soon as the CAT6 cable was replaced, it came online once again. In thinking about this situation, it does not make sense. It is not like there is a tremendous amount of data that is being passed over the T1.
The only conclusion that we could make was that perhaps the signal of the data coming off the smartjack is too degraded to traverse the CAT5e cable and the higher integrity CAT6 cable is capable of passing enough signal to make the uplink. The moral of the story is that if you are experiencing problems with receiving uplink from your T1 trunk to your Shortel system, you might try a CAT6 cable instead of CAT5e to make sure cabling/signal, is not the issue.