Hello,
I’ve noticed there was no tutorial showing how to deploy Teams / Phone System from scratch so I’ve created one. A test environment can be easily created with an Office 365 trial and even phone numbers assigned to the system with a calling plan with no costs under the trial period. I highly recommend watching so you get up to speed how to use Teams as a phone system replacement.
I hope it is useful for you, it is my first attempt creating a tutorial.
I’ll do some Yealink Teams phone review later on as well when I have a chance.