Room for cautious optimism with the solution to the problem of nuisance disconnects fom BT Internet Anytime ISDN.
I always felt that the problem I described above might just be with my equipment. I have Win2K with a fairly old Hayes Accura external ISDN TA in the serial port of the Dell Dimension PC running at 500MHz. So I didn't get around to complaining to BT.
Win2K doesn't support serial ports so the interface between the OS and the physical serial port is a "virtual" port.
So I bought a Hayes USB TA from PC World for £50 (GBP) and so far have had no serious problems. Tricky to install and it appears as a Network Adapter not a modem in the hardware. I needed help from Hayes Tech Support because the InstallShield routine was poorly written.
If the problem hasn't really been fixed, then I will have a stronger case to take to the BT complaints people. I'll report back after a decent period of trial.