Can't Receive Faxes

I set up MS Fax using Windows XP Pro. I can sent faxes fine. I cannot
receive faxes. I a using a phone line that is also a DSL line. I get a dial
tone fine, modem dials, and I get a message that states that the fax was not
sent.

I have two in line filters on the DSL line. I tried receiving without the
filters. No dice. I tried receiving with only one filter. No dice.

I have automatic answering set to 1 ring. I have tried two rings. I have
tried manually answering the fax. All failed to recieve.

The modem answers the call, but won't accept the fax.

Yes, I checked the box that allows faxes to be received in the configuration
wizard.

I am using a U.S. Robotics USR 5699B modem.

I am baffled.

Thanks.