If your phone is not supported and is not on the List of Tested Phones with RingCentral but you still would like to try to provision it with RingCentral as a 3rd Party unsupported phone, it will need to be added to the account as an "other phone".
Once the "other phone" is added, you will then login to the IP Address of the device and input the provisioning information that the system provides. As long as the phone lets you enter the phone registration information so it can contact our sip servers, this should not be an issue. However, as it is an unsupported device we cannot guarantee that it will register correctly with the system, nor that the phone will get all of the RingCentral functions or features.
This thread will have examples of how the below information is entered into an IP Address.
How do I manually provision my supported 3rd party Cisco or Polycom