Own moh - instead of remote moh

we are using asterisk 1.2.29 bristuffed 0.3.0-PRE-1y-s with freepbx for a handfull of our customers. Almost evereything is fine.
Some of our customers complain that in some cases they are not hearing the remote site’s moh, wenn they are put on hold - instead they are listening to their own moh.

Could anybody please give us a hint how to setup asterisk / freepbx so that the remote site’s moh is forwarded to the user.

Kind Regards,