Hi All Well reading though the forums looks like my boss has picked the most complicated phone going to try and test out 3CX setup before going live. I have managed to get everything sorted now, apart from one issues which is Every now and again, the phone will show in 3CX as not been registed, this from what I can tell stops the phone from getting calls. The phone can still make calls. Reboot the phone, and it then works fine. In the server event log it gives me event ID 4101 06.59 extension 105 is unregistered, removed contact: Sip firstname.lastname@example.org:5060 transport=UPD then I get 07.27 extension 105 is registered, contact email@example.com:5060 transport=UDP Now I did some googling and found someone said that 3CX expects a keep alive request from the phone to the 3CX system, and they advised to add the below line into the phone config. <timerRegistrationExpires>100</timerRegistrationExpires> Looking at the phone, it goes from Registered (idle) to Not Registered after about 30min or so. but this dosnt look like its fixed the issues.... Any help anyone can give would be very welcome.