Gotta love troubleshooting. Did we take a known working phone and put it in the port you are having trouble with? You said you swapped phones, but it's not clear. So, if you have two phones that work fine all the time, put one of those there and put the one that crashes in what we suspect might be a bad port. Put one of the phones that does crash in the good working port. See if the problem follows the port or set.
Could be card, could be port, backplane, etc. You have enough cards and ports to play with it sounds like, so you can swap around and test. I always take the system down (after backup) and re-seat all the cards. Sometimes dust/dirt can get in there and make problems. Make sure the sockets on the backplane are clean. Re-install the cards in the same configuration and test. I find it best to make one attempt and test unless you are really pressed for time or performance, then I can learn what it was that caused it.
Does it do the same thing when the phone is plugged directly into the card with a factory cable? Cable plant can cause wierd things, try it right at KSU and make sure you don't have a cable issue.
Hmm you didn't say what order the stuff is in on the 5 slot carrier, I'll assume you have the cards in the correct slots.
You said you have two 206's, are these three extensions on the same card? Maybe power down and swap the two 206 cards and see what you have?
Good Luck
It is only my opinion, based on my experience and education...I am always willing to learn, educate me!
Daron J. Wilson, RCDD
daron.wilson@lhmorris.com