Modem disconnects in 7.1

Hi all, I have 7.1 installed on a pentium 3 machine and which has an external modem. Using kpp, I can dial out and get a connection, but then the line immediately disconnects, before sending the login strings. This worked fine with 7.0, and works with other distributions - just not 7.1. Any ideas about what I can check ? Thanks, philomena