No Audio Problem

I am using asterisk & experiencing no audio my provider support only G.711 u-law
I can make call without problem but can’t hear voice my provider told me you are sending G.711 A-law. That’s why you can’t hear voice. Below is my setting can somebody solve this problem.
I didn’t see any error on asterisk console while making call.

[route-usa]
type=peer
callerid=“Name” <1321>
host=2XX.XX.XX.X
regcontext=internal
dtmfmode=rfc2833
disallow=all
allow=ulaw
;canreinvite=yes
nat=yes