I have switched to using GNOME and wanted to use the RH PPP Dialer. I went through the Dialup Configuration Tool, created my account and let it auto detect my modem. If I choose the Debug button on the Internet Connections screen, it starts the modem and makes a connection. However, when I select the RH PPP Dialer and choose the connection, it says it cannot start the connection. The modem shows no signs of being accessed.
Try to disable dial on demand ? (I don't exactly remember the name of the configuration option) IIRC, this problem hit me one day (who knows why since it used to work !), until I changed that setting.
I have had a similar problem which I noticed when 7 first came out ... The reason I didn't mention anything earlier was it suddenly worked one day, so I dismissed it as something I did. Well.. I recently did a fresh install and the same thing happened.(failed to activate interface)..... Another thing that was interesting was if I entered my dns numbers in Network Configurator I would be able to open Netscape and go to an address after the rp3 failed to activate.... What would happen was it would dial out...strange. Turns out the reason I got it working before was I downloaded and compiled a 2.4 kernel, booted with it and tried the Dailup Configuration utility from scratch again. That's all it took. Once I had this interface working I tried booting from the stock 2.2.16-22 kernel and it worked without any problems as well. I hope this will help in some way.
Closing at customer's request.