8.2.8. Activation of the voice compression 
In HG 3500, voice compression is activated in the AMO CGWB (ASC branch).
The parameter CODECLST is relevant for this setting. The codec sequence
is important in this regard. In the example below, HG 3500 uses G.729
as first choice, G.711A as second choice, and G.723 as third choice.
The codec that is actually used depends on the settings of the remote
system (user).
CHANGE-CGWB:MTYPE=CGW,LTU=<ltunr>,SLOT=<slotnr>,TYPE=ASC,PRIO=PRIO1,CODEC=G729;
CHANGE-CGWB:MTYPE=CGW,LTU=<ltunr>,SLOT=<slotnr>,TYPE=ASC,PRIO=PRIO2,CODEC=G711A;
CHANGE-CGWB:MTYPE=CGW,LTU=<ltunr>,SLOT=<slotnr>,TYPE=ASC,PRIO=PRIO3,{354}CODEC=G723;