T:38 FAX Support In Asterisk 1.8 (Trunk) Hello res_fax, Bye app_fax!

T:38 FAX Support In Asterisk 1.8 snapvoip.blogspot.com
Yes we all wonder when is this thing called FAX is going to go away. But in this age of multitude of communications possibilities, you walk in to any office, you will see a FAX machine. Those printers that call themselves multifunction Printers are doing brisk sales and just last week I helped a friend plug one of those in to a Vonage gateway.
So we have written about T:38 Fax Support in Asterisk many a times (Faxing With Asterisk) and looks like we continue to do so. Because all those Fax machines and also because Asterisk continue to support it, even from the Asterisk 1.8 trunk
Combining the desires of all sorts like better commercial FAX for Asterisk,  to have solid FAX support in Digium's commercial PBX products, and most importantly to get open source Asterisk (and its community of users) be able to use FAX over / through Asterisk reliably with Asterisk or non-Asterisk endpoints.
Asterisk 1.4 could pass t:38 fax pass through over SIP channels and with Steve Underwood’s spanDSP library support to send and receive fax over G 711 TDM links.
Asterisk 1.6 got the SpanDSP application merged into Asterisk Addons and went on to become ‘app_fax’ module. This allowed Asterisk applications to actually be T.38 endpoints; this resulted in the ability to send and receive FAX over audio and T.38 links. There were various bug reports and fixes that culminated once the society at large started using the Fax on Asterisk. All the hard work has led us to find that FAX over T.38 in Asterisk 1.6.0 and 1.6.1 works.
While all these faxing back and forth going on, Digium developed res_fax and res_fax_digium.

res_fax is similar to app_fax, in that it provides dialplan applications, dialplan functions, and other associated components to send and receive FAX. However, it does not actually include any FAX stack

And the other did.
So Digium after working hard on removing all possible obstacles have decided to open source res_fax. This you will find in a new branch in Subversion (/svn/asterisk/team/group/res_fax) based on Asterisk trunk, and carries the most recent version of res_fax in it.
So by the time Asterisk 1.8 is released, we will say good bye to app_fax and embrace res_fax. But to get the house in order we will need a res_fax_spandsp plugin module and the developers are invited to work on it, sooner.

But you will have firm support as "Kevin Fleming" has worked on this over the past 6-8 months, and willing to work with developer who will step up to the task.

You will find a more descriptive article over at Asterisk Blog.