choose codec binary appropriate for your Asterisk version 13 and CPU type, use x86_64 for 64-bit mode (use the command lscpu to find out the CPU type of your server), example:
[root@jessy bin]# lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
delete old codec_g729*.so files (if any) from /usr/lib/asterisk/modules directory
copy new codec_g729*.so files into /usr/lib/asterisk/modules directory
restart Asterisk
service asterisk restart
check the codec is loaded with ‘core show translation recalc 10’ on Asterisk console
Now you can use the g729 codec in the trunk settings
