What do I need to get the Fax option to work?

In every extension there is the option to receive a fax. I read that all that is needed to use this is to point a DID to it. So I try this with a pots line coming into a Grandstream GS400. I fire up my fax machine and dial the DID and nothing. So I have a couple of questions:

  1. Does this work without the Fax Pro module

  2. What are the requirements for the Fax line itself? I am assuming that a SIP trunk is out of the question. In another system I have used We could only use a DID from a T1/PRI.

Thanks for any guidance

I have a SIP only configuration. My FAX receive extension works fine. Some fax machines don’t like the software based fax server on my Freepbx box… but 90% of the faxes get received just fine.

When I dial my FAX extension, I get a 1 or 2 second pause and then the fax tones start up as it asks for a fax to be sent.

I’m just using the standard ( non pro ) fax stuff.

I didn’t do anything special… I’ve had this setup for over a year.

I am running the 2.11.x freepbx code with asterisk 1.8.


When you enable fax for an extension, a new type of destination is created for faxes. You have to route your DID to FAX -> Extension#.

My understanding is that if you are connecting a ‘fax machine’ to an ATA you are just registering the ATA with the extension and you do not allow fax recognition on the software side since the fax machine will worry about that part (although you may have to worry about codec choice and T.38 passthrough issues). If you are wanting a .PDF file of a fax sent to your email inbox, then use the FreePBX/Asterisk fax recognition solution in the post above.

It sounds like I can get this to work. Here is the scenario: I have a customer that I will be selling a system to (Freepbx of course). They currently have a phone line provider that takes a fax call and turns the fax into a PDF and emails it to a single destination. So from what everyone has said I take it that I can do the same with the built in Fax software and not need the Fax Pro.


yep… now you probably need to have a dedicated DID to be a fax extension. I tried haveing general extensions ‘check’ for faxes… but I’d get those anoying fax tones a lot so now we have a dedicated fax extension. When it answers, it does the software fax tones and recives the fax. Once reived, it emails a pdf to the office secretary.