Programatically Registering Yealink Phone

I am posting this here because I wonder if I can use the EndPoint Manager or RESTFul Phone Apps.

I wonder if anyone has any suggestions for me. I am working with a Yealink 41g, FreePBX 12 and a custom .NET CRM. I want to allow the CRM to change the phone registration information based on an extension associated with the CRM user. I know how to set DND, dial and transfer calls via the API, but I can’t figure out how to change the SIP registration info on the fly.

Any suggestions would be greatly appreciated.