Trusted SSL Certs

[NickS]

Hello,

I'm trying to set up our PBX in the cloud, and one of the most important things in this case is security. We need communications between the server and the phones to be encrypted and secure, however when setting up the server with a GeoTrust Global CA cert, the test phone I have here (a T48G) does not accept it as a trusted Cert. It will not autoprovision until I turn off "accept trusted certificates only".

The Cert is GeoTrust Global CA with an intermediate. The phone server is 3CX, but I don't think the issue here lies in the server, which is why I'm coming to Yealink. Is the issue here having an intermediate?

What is the recommended method of going about getting a cert from one of the trusted CAs?