Nortel MICS phones resetting / flashing

[peteppg]

I have a Nortel Norstar MICS R3.0 that has been in since 2007 without changes. Recently we have had random sets reset/flash then come back to life, (not all sets affected, maybe 5 of 30) sometimes while on calls, and the caller is still there when the set comes back to life, sometimes they reset when idle. We swapped out phones, swapped ports, reconfigured ports, and finally swapped the power supply. All wiring is newish cat 3 home run terminated on 66 blocks.
All sets are on the core KSU, and are behind a APC battery backup power supply. Next stop a full system restart. Anybody got anymore ideas?

 

[fonegal]

I have run across this before and it almost always comes down to a power issue on the ksu's main motherboard,try swapping out the ksu and I would also consider replacing the software as that is a really old version released in maybe '92 or earlier.Make sure that the amphenol cable has the retainer clip screwed in tightly or the cable may have worked loose, it will be the one at the top of the cabinet.