My modem has been working for 4 months - then I found there was no dial tone and no calls could be made or received on the house phones while the modem is connected. Unplugging the modem from the phone socket retores the dial tone. If I plug it back in and IMMEDIATELY click on connect, I hear the dial tone and the modem goes through its usual dial up and connects. If not the dial tone fades away and it sounds as if I have a connection to an 'empty room'. The dial tone cannot be restored until the modem is unplugged. I have another modem on an old system which works without any problems, using the same cable and phone connection. The problem modem is an internal 'Soft 56 Data Fax Voice Speakerphone CARP'. Device Manager says there are no conflicts & it is working properly, - COM 3. I am using windows XP (home), AMD Athlon xp 2500, 512Mb memory, 80 Gb hard drive. System restore has no effect. Only 2 phones and modem on BT line which has been checked as OK. I will appreciate any suggestions to help me find the cause of the problem please.