How to make wvdial check for the presence of a dial tone BEFORE dialing?
 

Hullo all,
I have on demand ppp access to the internet. According to my logs wvdial is the app dialing my isp. I share the phone line with house mates and they are usually a bit peeved whenever I don't track the phone down to see if someone is using it before I dial out. According to wvdial's man page its an "intelligent" dialing program that can detect the absence of a dial tone. But presumably it only performs this check after it dials the number. Can I configure it to ensure that it detects a dial tone before it dials?

This seems like a very obvious function but it isnt a default of the program's opperation. I know the frequency of my dial tone so it'd be straight forward enough to write a program that checks for the correct frequency before allowing wvdial to dial out, but if its a standard op of the program I don't want to bother.

Can I configure wvdial to ensure that it detects a dial tone before it dials?