To install the G.729 codec, you must first order licenses from Digium. They will then send you an email with the license key. When you have received it, then:

For Asterisk 13:

• enswitch install g729-13

For Asterisk 11:

• enswitch install g729-11

Then follow the menus to register the license key. When finished, add the following line to the bottom of the [general] section in /etc/asterisk/sip.conf and /etc/asterisk/iax.conf:

allow = g729

then restart Asterisk if you have already started it.