I assume that your phones are connected via a modem/router - have you tried restarting it and/or checking that the firmware is up to date? The you could try disconnecting all the phones and BeoTalk, and then trying them one-by-one to see if CLIP works individually.  Perhaps one of them is supressing the CLIP signal. You could also try a reset of the BC6000 handset and/or its base:  (make sure that you have backed up phone contacts if they are stored on the base): - Reset base: Press (dot) 7 000 8 - Reset handset: Press (dot) 7 000 9 You could also try replacing the batteries in the BC2500s.