Does anyone out there have any familiarity with AT&Ts ISDN 81510 or 8520 sets. I've got half a dozen (out of 4000 or so) that are constantly resetting (mostly overnight).

You leave at 17:00 and your phone is OK. Come in at 08:00 and your phone is dead. Unplug it, replug it and it comes up fine.

I'ver tried all the usual stuff and haven't found anything yet. All the replacement sets I have are old (8-10 years) & used. Before I start wholesale replacement of phones with Tone Commander 6210/20 sets, I'd like to know if anyone has seen this sort of thing before.

TIA,

Sam

"Where are we going and why are we in this hand basket?"