FAX machine mystery

[TheMacintoshLady]

     Hello,

I am having a fax machine mystery. I used to be able to fax to and from 
any standalone fax machine from my eMac on FAXstf 10 or from my 
Wallstreet from GlobalFax 2.6.9 for internal modems. I can still 
sometimes do it from the latter.

I can fax between the two machines perfectly but keep getting the no 
carrier signal when using the X machine to try to fax a Class 3 
standalone machine.

One of my machines was connected to a phone line with an answering 
machine but it worked fine.
What could be wrong?