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 this, do this if running Asterisk 1.6.2:

• enswitch install g729-162

or this if running Asterisk 1.8:

• enswitch install g729-18

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.