[Asterisk-Users] How do I show that a message is waiting on a Zap channel?

[Michaël Gaudette]

I have an FXO card, with a typical modern PSTN phone connected to it.  A
phone that, when connected to my PSTN provider, will show when there is a
message waiting by flashing a red light.  

If I connect this phone to Asterisk, with a Zap channel, how do I make this
phone recognize that there is a voicemail waiting, and flash it`s red led?  

Mike