Does the modem handshake?
Check modem type.
If applicable try kfex number.
Still not working?
Recreate the dialer.
Still not working?
Re-install Dial up Networking.
Check number being dialed.
Still not working?
Check for Modem init strings (If init string entered - Replace with AT&F1.)
Still not working?
Recreate the dialer.
Still not working?
Drop connection speed to 19200, remove error control add AT&F1 to extra settings remove software compression from the dialler.
Still not working?
Check for winsock2 on Win95 on Win98 remove winsock2 reg key and re-install DUN.
Still not working?
Modem problem go to modems cluster (error code).