We have a UC560 with an ISDN30/E1 connection to the PSTN. We have incoming calls routed through to 8 x SPA525G2's in a blast group. I have debugged the ISDN and every thing seems to be OK there but we are dropping an awful lot of incoming calls. Generally what is happening is that all 8 phones will ring but when you pick up the receiver the line goes dead!! This is an intermittent fault, any pointers would be much appreciated.
