Do you have multiple registration enabled?  I don’t think it is on by default, so that could definitely cause what you see.  Check internal.xml:

<!-- Can be 'true' or 'contact' -->

<!--<param name="multiple-registrations" value="contact"/>-->

From: freeswitch-users-bounces@lists.freeswitch.org [mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of Vitalii Colosov
Sent: Friday, October 01, 2010 12:00 PM
To: FreeSWITCH Users Help
Subject: [Freeswitch-users] Simultaneous ring of all phones registered with the same extension number

Hi,

Could not find this answer, so would appreciate any hints.

I have registered 2 sip phones using the same extension number.

When I dial this extension number, only one sip phone rings.

However I need both of them to start ringing.

Is it possible, that when I dial the number - both other phones will ring, not only one..? 

And when I answer on a phone, another one would stop ringing.

Thank you,

Vitalie