Per Extension Fax Capabilities

I have a PBX that I am setting up for a customer with 100 users. The business requirement is to have the ability for each user to have a phone extension and personal incoming fax capability. I have successfully setup an Inbound Route to receive faxes as defined in the “General Settings”. What I need to know is if the possibility to make each extension capable of receiving faxes for the individual user?

My configuration is TrxBox 2.4 CE, FreePBX I am using SIP trunks for all outside connectivity.

On the Extension Screen (5600), I set the “Fax Handling” as follows:

Fax Extension: FreePBXDefault
Fax Email:
Fax Detection Type: NVFax
Pause after answer: 6

When I call that extension (5600), the phone rings (20sec), then goes to VM. If I answer the phone, I can hear the sending fax machine sending tones, but the extension doesn’t receive the fax.

Is this setup right (probably not :slight_smile: ) and/or what is the best way to manage the requirement I am trying to accomplish?

Ideally, a call comes in to an extension, the extension listens for fax tone for ~6 seconds and if no fax tone then the phone rings.

Thanks in advance!


“I am using SIP trunks” is most likely the problem. The capability to recieve a fax is inversly perportional to the compression used.

i.e. 0% compression, near 100% likely, any compression suddenly takes it down to 50%, more compression clode to 0.

A Fax needs to hear continious tone, compressing changes the tone and signal slightly so that it falls out of spec and can’t be detected any more.

To clarify my problem. I can successfully receive faxes via the FreePBX “system” fax handler. The SIP trunk provider is using g711u. My problem seems to be around the extension fax handling setup rather that the overall fax reception (like I said, I receive faxes to the “system” handler). Any other possibilities or insight on how the “Fax” section of the extensions management form is supposed to work?

Well as long as you are doing ulaw you should be ok most of the time…

It all Depends on how you are setup. If you have DID then create a inbound route for that DID, have it check for the fax at that point, then set the e-mail, etc so it goes to the particular person instead of the system default. If it is NOT a fax then forward the call to that extension.

Getting fax to work for the first time is tricky
Here are things you could check

at the command prompt
asterisk -vvvr

After you get connected to asterisk command line type
show applications like fax

For the FAX to work you should have these
NVFaxDetect: Detects fax sounds on all channel types (IAX and SIP too)
RxFAX: Receive a FAX to a file
TxFAX: Send a FAX file

Step 2:
Assuming that you have the above;

  1. If you are using a SIP based provider; In your Trunk Definition make sure you have
    g729 will not work for fax;

  2. Create an Inbound route with the DID number and select the fax as NVFAX . Give the email address of the person whom the fax is sent to in fAX Email; put 5 seconds PAUSE AFTER ANSWER;
    In SET Destination; select the extension number; that you want this DID to be rung to.

  3. If you are using ZAP channels instead of SIP; select 0 in seconds PAUSE AFTER ANSWER