Call dont pass through G729 and G723

I just installed G723 and G729 on my server.But when i tried to call using a soft dialer it fails with a message saying “not acceptable here 488”…How can I fix this?
When I entered “core show translation” in asterisk (after downloading and executing the codec) i find that it was installed.But i cannot make the call using G729 and G723.Plz Help

Asterisk 1.8
CentOS 5.7