AN URGENT - Fax wont Send in XP Pro - Issue

I have XP Pro with Service Pack 2. I have just installed optional Fax
Service. I have
56k Ext US Robotics xx1663xx Sportster Flash Modem. When I try to Fax from
Word or Fax Console, Nothing happens! Nothing to Outbox. As you push SEND
the fax just vanishes. Nothing at all happens in the Fax monitor. No activity
with the modem or the Outbox. Nothing. I can get the modem to dial the
internet through via
network connection. No joy via Fax or Net Op (PC Anywhere type software).

THIS IS NOT a Modem v's XP compatability issue as Crey Frisch [MVP]
suggests. as it works in other XP machines. PLus I have now tried 3 different
modems in the XP Pro PC all with the same results. IT JUST DOESN'T Dial ...
NO ACTION WHATSOEVER. PLEASE HELP ME SOMEONE !!!!!