Here is a link with some explanation why plain FAX over VoIP shouldn't be expected to work most of the time: http://www.soft-switch.org/foip.html

I have a VOIP PBX onsite, using CommuniGate Pro. I'm wondering if I can just connect a fax machine to an ATA on my network and send a fax, or if the ATA, my SIP server and my VOIP-PSTN provider have to support T.38 all the way through for fax to work?

To: Amber
From Andre

So fax over ip works..!! My question is: what kind of mdem/rouer are you using? I'm using a Sweex router (LB000021) and a Linksys PAP2 ATA box.
I hav no problem with sending a fax but receiving a fax is a big fat NO on my end...

I'm not sure what could be the problem...

Thank you...

Fax over voip works for me just great! Many voip consumers have questioned if the voip will work and I haven't had any problems with NexBoom's service. I have a Xerox all-in-one fax that plugs directly to my voip line throught the router. I receive faxes by email and can send them straight over voip from my fax machine. What is the fuss about fax machines not working? I have been told that some people have to slow down their bps on their machines. I understand that it is a digital signal and could get scrambled, but why do some work and some do not?
http://www.voip-boom.com
Faxing with voip has no issues on my end how about yours?

Pac-West has great local rates @ $.003 and greast coverage of local DIDs. Call 209 926 3147 or shutch@pacwest.com for further details. Great application for FoIP companies looking for termination.

I need more details on the FOIP mail me
skyagbi_61@yahoo.com