I've currently swapped OS from 2008 r2 to 2008 Standard 32 bit. I've setup roles, attached the server to a domain (controlled by a server 2003 box), setup rights for users to be admins (in my desperation) to the fax.
I have a US robotics PCI card setup on the 2008 box, shared the fax, setup for receiving, and setup a role for US dialing. I can send and receive locally on the 2008 box no problem. When I "add" a fax/printer on the XP box it sees the path, recognizes it as a fax modem, pulls up the local Windows Fax and Scan, goes through it's motions, and when I hit "SEND", the fax goes away. No Outbox, no Sent items, nada. I checked the fax server, no errors, no faxes pending.
I took the microsoft recommendation of pulling some drivers on this thread: http://social.technet.microsoft.com/Forums/en-US/winserverprint/thread/725a0c16-ca92-4ccd-8e43-94609c238f31/?prof=required to no avail.
I did get 1 error on the initial send from the XP machine: "the outgoing routing role is not valid because it cannot find a valid device". There was no such error on the fax server, nor have I seen the error on the XP machine event viewer since in subsequent attempts. Is there a local rule I need to change on each XP machine, or am I missing an easy step somewhere?