error in sending fax

Hi all;

I have been sending faxes from my windows xp ,there has not been any problem but not since few days after I converted my broadband connection into wireless one by using a router,while sending faxes,I can hear dial tone ,i can hear the other side answer but before it says sending page 1 or sometimes during it there is a message saying error occured.
I am failing to understand the nature of this error.

If anyone could shed some light on it??