On October 31, 2018, Microsoft Office 365 will be disabling support for TLS 1.0 and 1.1. This means that, starting on October 31, 2018, all client-server and browser-server combinations must use TLS 1.2 or later protocol versions to be able to connect without issues to Office 365 services. This may require certain client-server and browser-server combinations to be updated.
At a high level, this requires installing Skype for Business Server 2015 CU6 HF2, applying pre-requisite updates to .Net and SQL, and finally another, separate round of OS configuration updates, i.e. disabling TLS 1.0 and 1.1 via registry file import. It is critically important that you complete installation of all prerequisites, including Skype for Business Server 2015 CU6 HF2, prior to disabling TLS 1.0 and 1.1 on any server in your environment. Every Skype for Business Server, including Edge role and SQL Backends, require the updates. Also ensure that all supported (in-scope) clients have been updated to the required minimum versions. Don’t forget to update management workstations as well.
And then read part 1 here for more background specific to SfB/Lync and the supportability statements
Part 2 here gets into the weeds a bit on “How To Achieve”.
Part 3 will be published at a later date.
Here is guidance for Lync Phone Edition (LPE):
General TLS1.2 whitepaper:
Here is the Microsoft Exchange equivalent:
If you or your customer is doing anything with Office 365 hybrid, then you need to be reading all of this and figuring out your next steps.