using FAXCOMEXLib;
...
FaxDocument fd=new FaxDocument();
fd.Body="c:\\a.tif";
fd.DocumentName="My First Fax";
fd.Priority=FAX_PRIORITY_TYPE_ENUM.fptHIGH;
fd.Recipients.Add("10101010"/*fax nr*/,"Nelutzu"/*nick name*/);
fd.Subject="Fax de test";
int response=fd.ConnectedSubmit(fs);