Okay, I would check the iPockets. It might be that someone kicked out the power plug long enough for the settings to default.

I would put a 9-pin null modem cable from the iPocket to my laptop (preferably on an HTG 9-pin serial if you still have one) and open hyperterminal. See if you get data out, and if so, at what baud/parity. You might also have to go into the iPocket setup/programming and verify settings.

Also, has anything happened to the layer-2 switch that all of the iPockets and the PBX plug into?