Hi,
This is not a phone problem. If you are register multiple ip phones (SIP) to a single extension, the last who registered will get the incoming phone rings. If you want to use hot desking with the Freepbx framework it is better to use device and user configuration.
Just keep in mind that this feature will not be supported any longer on the newer releases of the Freepbx. What is your main problem now? not enough seats for all the agents?
Thank you,
Daniel Friedman
Trixton LTD.
Mobile: +41.79.868.7050
Email: dani@3xton.com