I have tried this a few times and for some odd reason it does not work with my system. Here is what I do in order:

1. Under System/extension list/hunt group members. Create a list with the 3 extensions I want to ring at once.

2. Under System/Hunt Groups
Create a hunter group and add the hunt group member extenion I just made.

Done....but if I dial any of the extension I listed in the first step it rings all alone. What am I doing wrong?? Anything will help, thanks so much.