Russell Bryant has reported that official support for MFC/R2 signaling in chan_dahdi has been merged and that is available right now and the commit, "Add MFC/R2 support for chan_dahdi." is on this post to the list.
We are also informed that R2 signaling in chan_dahdi will be included in Asterisk 1.6.2. The modifications to chan_dahdi, and the supporting library, LibOpenR2, were both written by Moises Silva.
The code could be checked out from SVN at 1.6.2 branch and you will need to install LibOpenR2 the supporting library.
Readme for 1.6.2 branch is here.
Russells post MFC/R2 support in Asterisk 1.6.2
Wednesday, March 18, 2009