[asterisk-users] Inefficient Codec Translation

[Jim Boykin]

We run asterisk to handle incoming DIDs and we have observed
inefficient Codec Translation.

Here is the scenario

[DID Vendor] ---------------------------> [Asterisk ]
------------------------> External GW [G729]
                                                                      |

|-------------------> External GW [iLBC]

Our DID vendor and asterisk box supports both ilbc & g729. However,
our external gateway termination supports either ilbc or g729 (and not
both) and depending on users location, we terminate it on either
gateway.

Since DID and asterisk box supports both the codecs, we assumed that
asterisk will appropriately select codecs depending on where we
terminate the call so that no codec translation happens. However, this
seems to be an incorrect assumption and we see that different codecs
get selected on two legs which leads to quality drop and extra CPU
cycles.

May be we are doing something wrong. Pls suggest what we are doing
wrong. Below is asterisk configuration.

[did]
type=friend
host=xxx
canreinvite=yes
disallow=all
allow=g729
allow=ilbc

[gw1]
type=friend
host=xxx
canreinvite=yes
disallow=all
allow=g729

[gw2]
type=friend
host=xxx
canreinvite=yes
disallow=all
allow=ilbc

Thanks
Jim