Fax with Asterisk 11


I installed Asterisk 11 on Ubuntu 12.04. It is configured and running successfully.

I want to configure Fax service with my Asterisk server. It should support T38 and able to send/receive through both analog and VoIP. I have gone through some stuff in internet and below are my queries:

  1. Is it possible to configure Asterisk fax service with Opal?
  2. Why should I use Hylafax to configure my fax service with Asterisk?
  3. Why should I use OpalVoIP to configure my fax service with Asterisk?
  4. What is T38modem (software)? Why I should use?
  5. I don’t want to buy Digium license for this and seems it is expensive. What are the alternative ways to do this?
  6. With out using Hylafax, T38Modem, OpalVoIP etc., is it possible to implement fax service with Asterisk? If so, what are the software that I need to develop?

Thanks in advance.



Any update would be appreciated. It would be really helpful for small hint also.

Thank you.


  1. What’s Opal
  2. Because it is free for multiple concurrent calls
  3. See (1)
  4. Google t38modem (that’s what I just had to do).
  5. As you’ve already listed, plus implement it yourself.
  6. Asterisk is open source, and, although the ITU-T specifications will be quite expensive, there should be sufficient open source implementations around to work out what they contain.

I don’t use fax with Asterisk but the extreme infrequency of references to even Hylafax, on this forum, suggests that most people consider the Digium product sufficiently better to justify paying for it.

Hello David,

Thank you for your reply and sorry for the delay.

OPAL (OpalVoip) implements the commonly used protocols used to send voice, video and fax data over IP networks.

I am still confusing with the flow or steps in sending the fax through Asterisk :smile:
Is it possible to implement my own fax service with Asterisk+OpalVoIP or Asterisk+HylaFax? Or Do I need any other application or software for the above flow?

Can you please confirm the flow. Please correct me, if I am wrong.

Thanks in advance.


For the internal flow, you need the developer mailing list.