Dial-up, 'Phone line-Modem problem...!

Hello Lads....
I have this annoying problem which has suddenly cropped-up....
When I am attempting to empty my bowels When I am connected to the Internet via 56k Dial-Up, and someone calls me on their 'phone, they hear a "Dialling" tone and wait for me to answer the 'phone...
Which annoys them when I don't...and they assume that I am dead!
Previously when connected to the 'net and someone 'phoned me they would get an "Engaged" tone indicating that my line was "Busy".
Which was correct...and they knew that I was OK...!!
Another clue: When I pick up my phone now while connected to the 'net, the line is quiet. Previously I would hear Internet data being sent down my 'phone line....which I should do...!
Is this likely to be a problem with my phone company, or a problem with the settings on my new US Robotics Modem, (Recently replaced my old Win '98 one).
Any ideas, Lads...?
Paul...Connected to the 'Net, and very much alive...!
I have this annoying problem which has suddenly cropped-up....
When I am attempting to empty my bowels When I am connected to the Internet via 56k Dial-Up, and someone calls me on their 'phone, they hear a "Dialling" tone and wait for me to answer the 'phone...
Which annoys them when I don't...and they assume that I am dead!
Previously when connected to the 'net and someone 'phoned me they would get an "Engaged" tone indicating that my line was "Busy".
Which was correct...and they knew that I was OK...!!
Another clue: When I pick up my phone now while connected to the 'net, the line is quiet. Previously I would hear Internet data being sent down my 'phone line....which I should do...!
Is this likely to be a problem with my phone company, or a problem with the settings on my new US Robotics Modem, (Recently replaced my old Win '98 one).
Any ideas, Lads...?
Paul...Connected to the 'Net, and very much alive...!