Hi,
There are two possibilities:
Create a ring group in the Freepbx and add all the extensions that you want to call.
a. Upon creation the ring group, set the number of the ring group (usually 600, but you will see it after its creation) in the door station settings.Set the follow-me module of your extension to ring all the extensions that you want (a mini ring group).
Thank you,
Daniel Friedman
Trixton LTD.
Mobile: +41.79.868.7050
Email: dani@3xton.com