asterisk users - Jul 2006 - Detecting voicemail from CO on FXO port and passing to H.323 phone. Possible?

The subject pretty much describes what I need to do.

Basically, I want to be able to detect that there is voicemail waiting at 
the CO on an FXO port and somehow flash the message waiting light on an 
H.323 phone (or any other type of phone)

I my case, the CO is actually a legacy POTS based PBX and I've just 
plugged the FXS station ports into my FXO ports on asterisk. The PBX is 
able to set the MWI lights on my POTS phones so I know it has the 
capability to "tickle" the FXO port on my asterisk box. What I
don't know
is how to detect that in asterisk and then tell the H.323 phone to flash 
its light.

Any clues would be appreciated.

Bob.

> Basically, I want to be able to detect that there is voicemail waiting at
the
> CO on an FXO port and somehow flash the message waiting light on an H.323 
> phone (or any other type of phone)
I assume that by the lack of response, there is no way to pick up on the 
vocemail waiting signalling from the CO on a FXO zap channel. Can somebody 
confirm this.

Bob.