This patch adds AMR-NB support to Asterisk 1.4

(for Asterisk 1.6 check out asterisk 1.6 branch and use the
asterisk-1.6-AMR.patch patch (provided by Ivelin Ivanov))

1. create the asterisk directory

$ mkdir asterisk-1.4-SVN-AMR
$ cd asterisk-1.4-SVN-AMR/

2. checkout fontventa repository

$ svn checkout http://sip.fontventa.com/svn/asterisk/ fontventa

3. checkout Asterisk

$ svn checkout http://svn.digium.com/svn/asterisk/branches/1.4 asterisk
$ cd asterisk/

4. add AMR to Asterisk

$ patch –dry-run -p0 < ../fontventa/amr/amr-asterisk-patch.txt
$ patch -p0 < ../fontventa/amr/amr-asterisk-patch.txt
$ cd codecs
$ ln -s ../../fontventa/amr/amr_slin_ex.h
$ ln -s ../../fontventa/amr/slin_amr_ex.h
$ ln -s ../../fontventa/amr/codec_amr.c
$ mkdir amr
$ cd amr
$ wget http://www.3gpp.org/ftp/Specs/archive/26_series/26.104/26104-700.zip
$ unzip -j 26104-700.zip
$ unzip -j 26104-700_ANSI_C_source_code.zip
$ ln -s ../../../fontventa/amr/Makefile
$ cd ../..

5. build Asterisk

$ ./configure
$ make

6. configure AMR
app_h324m and app_mp4 encode AMR inside the ast_frame in RTP octed aligned mode. (RFC 4867 section 4.4).
To configure the AMR codec to use octed aligned mode add this to codecs.conf:

[amr]
octet-aligned=1