I have two ATA 186's registered to a Callmanager V7.1. We are located in the UK. When I plug a modem into the ATA, I get dial tone, the device dials, . and the modem handshake begins. The handshake caries on for some time until the other side hangs up. If I plug the modem into a reguar analogue line the call goes through just fine. There is obviuosly a setting that is not correct, however I don't see anyway to adjust impedance or anything. Why isn't this working and how can I fix it? Thanks for your help.