Microsoft announced that as part of their Exchange Online Unified Messaging solution, they are discontinuing support for Session Border Controller access.
What does this mean?
Exchange Online UM will no longer offer direct SBC access for third party PBX's. If you have a third party PBX, anything not Microsoft, you won't be able to integrate it with Exchange Online Unified Messaging. You will have to find an alternative approach.
This video explains the impact of Microsoft’s announcement, your options, and introduces AVST’s enterprise-class, highly interoperable unified messaging solution.