Yealink Phones and Rest API

I am trying to get away from Devices and Users for an existing customer. I have a system at the office that has 6.12 Asterisk version 1.8 with ALL the commercial modules installed. I have a Yealink T26 with the latest firmware on it. I have a key programmed for the Rest API / Login. I have several phones that are allowed to login. When I press the button to login I get the login with the user and password. I enter those and all the phone does is sit there, it never changes from that screen. The phone is initially setup with a default extension, I have even tried to logout first then login but to no avail. Is anyone else using these phones? I am replacing the customers system and I am going to 10.13 with Asterisk 13, but I need to know if this login will work since they use it many times a day already in D&U.