asterisk users - Jun 2005 - phone rings but caller doest hear it

Hela,

When I call my sip phone the phone rings and when i answer
it all works great however while the phone rings the caller
doesnt hear the 'beep, beep'  I've had this before and fixed it
too bad i can't remember how I did it ,
Anyone any suggesstions ?

some specs :
Freebsd 5.3
Asterisk 1.0.6
Phone :  ArtDio IPF-2000

-Armand