In Digium’s continuing quest to deliver you, our users of Free Fax For Asterisk, and our customers of Fax For Asterisk, with the best possible solution, we are pleased to announce the availability of version 1.2 of…(drum roll without suspense) Fax For Asterisk.
How has this version improved? Why, with new features, of course, hence the title of this blog post.
New features include:
- DAHDI Buffer Policy Implementation -Currently requiring the trunk version of Asterisk, in addition to the 1.2 release of Fax For Asterisk, new dialplan functions to allow the setting of buffer policies to prevent fax failures on higher latency systems, e.g.:
exten => 1234,Set(CHANNEL(buffers)=”12,half”)
where “12″ represents a number of buffers (each buffer is 20ms), configurable between 4 and 32, and where “half” represents the policy implementation, configurable as “immediate,” “full,” or “half.”
To use, simply set your buffer policy in your dialplan before any send/receive fax operation across a DAHDI channel.
- SIP Fax Detection Options -At present, also requiring the trunk version of Asterisk in addition to the 1.2 release of Fax For Asterisk, new options are available related to T.38 session initiation. Older releases of Fax For Asterisk only detect T.38 fax upon the receipt of CNG. In practice, we’ve discovered that a number of T.38 providers send T.38 invites immediately, and never send CNG to initiate a T.38 session. Thus, the faxdetect option in sip.conf can now be set to:
no – To disable all fax detection
cng – To trigger fax detection based on the receipt of a CNG tone
t38 – To trigger fax detection based on the receipt of a SIP T.38 invite, without CNG tone
yes – To trigger fax detection based on the receipt of either a CNG tone or a SIP T.38 invite.
These changes should improve our compatibility with the wild, wild west of T.38 implementations.
- New CLI Commands -New Asterisk command line interface commands are available to display the settings configured in res_fax and res_fax_digium, simply run:
fax show settings
to see your current settings.
- Asterisk CLI Type Column -A “Type” column is now displayed when “fax show sessions” is run on the Asterisk CLI, informing the user whether the fax is of type “G.711″ or of type “T.38.”
- ECM Configuration per Provider / Peer & Configuration Moved -Error correction mode may now be configured on a per provider / peer basis. This proves useful in the case that a provider does not implemented T.38 ECM properly. Digium has observed that ECM must be disabled for T.38 faxing to work properly with Gafachi.
Configuration of error correction mode has moved from res_fax_digium.com into the res_fax.conf configuration file. Note that the default setting is still to enable ECM.
- SendFax initiate T.38 re-invite -Digium observed that a number of providers or far-end systems did not send a T.38 re-invite and instead waited for the local system (Asterisk) to send it instead. The SendFax application now supports the “z” option to enable this feature. If the “z” option is set during a SendFax, then res_fax will initiate the T.38 re-invite if it is not received in 10 (ten) seconds from the far end. Digium observed that the “z” option must be used for T.38 faxing to work properly with Gafachi.
- Send / ReceiveFax G.711 Fallback mode -A new fallback option “f” has been added to the SendFax and ReceiveFax applications. In the event that T.38 negotiation fails, enabling this option will cause Asterisk to revert to audio fax mode. Digium has observed this is required for some providers, like BroadVox, who provide T.38 for inbound faxing, but accept only audio faxing for outbound.
Please note that audio faxing over the Internet is very unreliable, and Digium cannot provide support for fax failures due to poor Internet connections.
- New Debugging utilities -In order to make debugging easier, we’ve added two new command line capture options, one for audio faxes and one for T.38 faxes.
For audio capture, do “fax set g711cap on” in the Asterisk CLI and a stereo wav file will be created for each fax session. The resulting files will be saved in /var/log/asterisk/g711cap. To stop capture, do “fax set g711cap off.”
For T.38 capture, do “fax set t38cap on” in the Asterisk CLI and a Wireshark compatible pcap file will be created for each fax session. The resulting files will be saved in /var/log/asterisk/t38cap. To stop capture, do “fax set t38cap off.”
Ready to upgrade? Run right over to the Fax For Asterisk Download Selector and grab the new release.
As always, we thank you for your support.