There is a users mailing list intended for all discussion about IAXmodem at:
iaxmodem-users@lists.sourceforge.net
It is recommended that you subscribe to the mailing list before posting to it.
You can subscribe to the mailing list here: http://lists.sourceforge.net/mailman/listinfo/iaxmodem-users.
Before posting a question to the mailing list you may want to search the mailing list archives to see if the same question has already been answered before. Archives of the mailing list are available here: http://sourceforge.net/mailarchive/forum.php?forum_id=46841.
Web-based forums for discussing IAXmodem (in a blog-like fashion) are available here: http://sourceforge.net/forum/?group_id=148814.
If you wish to report a bug, request a feature, or submit a patch this is the place for that: http://sourceforge.net/tracker/?group_id=148814.