Sangoma VoIP Phones are fully compatible with freepbx and are set at an incredible price point. I can connect any of the 3 models available to the same pbx unit. Being a small company I purchased 5 of the S300s for my admin staff, 1 S500 for my business partner and an S700 for myself. Configuration was a breeze with the tools provided and we were given access to some really cool features which allows us to reinforce our global image at a fraction of the cost of engineers installing the system for us. All I had to do was populate the system with the PBX details as the Zero touch tool does everything for you so long as you follow the directions provided.