voice mail problem after adding a gateway

Submitted by pbxuser on June 11, 2008 - 6:07pm.

Hi guys, I am very new to asterisk so please bear with me. Here is my problem:
-We had an asterisk voicemail working and we were able to access our voicemail externally

-We added a media gateway (mediant1000), now asterisk is behind the gateway box

-We can make or get any kind of call through asterisk as usual. However we can not access our voicemail from external phones. It appears that since our voice mail number does not exist is sip.conf when asterisk gets that number from the GW it says it doesn't recognize that number.
Is there any way we can fix this issue? thanks,