How to have Microsoft FAx wait for dialtone before dialing?

Hi,

I am using Microsoft Fax to send faxes from my PC. Under my modem settings,
I have the ‘Wait for Dialtone beforre dialing’ box checked. However, when I
send a fax, it immediately starts dialing regardless of if some is on the
line or not which get annoying for the people on the line. Is there a
solution for this? Is there a modem string I can issue under advanced
commands to have my modem detect a dialtone before dialing out?

Thanks

Zoom