How to add a Mitel IP 485G phone that I need to add to my Ring Central Network?

Hi Everyone,

I have Mitel 485G phones and we use RingCentral. A few months back, I was following this guide to set up my phones in RC. These steps are no longer working for me. After I set the configuration server, the phone reboots and hits me with a “no service” message. 

Does anyone know of any other ways to add the phone to RC?

Thank you.