While both Skype for Business (SfB) Server 2015 and 2019 have been out of Support since October 2025, some of our customers who needed more time to finalize migrations to SfB Server Subscription Edition (SE) or to Teams opted to enroll into the Extended Security Update program. That ESU program started in October 2025, and is concluding at the end of April 2026.
As the end of ESU draws near, some of our customers told us that they will need additional time to finalize their SfB Server 2015/2019 migrations.
Today, we are announcing that we have created a “Period 2” for the SfB Server ESU program. This period will be another 6 months, lasting from the start of May 2026, through the end of October 2026. There will be no further extensions of this program after that.
Conditions of the “Period 2” ESU program
Customers who wish to enroll in the Period 2 program will have to re-purchase the ESU for the SfB servers they need to cover during Period 2. Period 2 is not an “extension” of the current (i.e. Period 1) SfB ESU program and your organization does not automatically enroll into Period 2, either. You will have to proactively purchase ESU specifically for this new time period from May 2026-October 2026 (in the same way that you purchased the original ESU).
It is not necessary to have purchased Period 1 ESU to participate in Period 2.
After a purchase is completed, the participating organization will receive information on how to download the updates released under the Period 2 ESU. The Period 1 ESU program instructions will not work for ESU updates released after April 2026.
Starting today, customers can contact their Microsoft account team to get pricing information and purchase Period 2 ESU for their SfB 2015 and SfB 2019 servers.
What does this mean?
- This Period 2 ESU is not an “extension of the support lifecycle” (Microsoft Lifecycle Policy | Microsoft Learn) for Skype for Business Server 2015 and 2019. Those servers are still out-of-support as of October 14, 2025, and you will not be able to open support cases for them (unless directly related to an issue with a SU released to ESU customers during the ESU period).
- This Period 2 ESU is a way for customers who are unable to finalize their migrations to SfB Server SE or Teams before the end of April 2026, to receive Critical and Important Security Updates (as currently defined by Microsoft Security Response Center (MSRC) scoring) during Period 2. If there are SUs that we need to release, we will privately provide such SUs to ESU customers only. SfB Server 2015 and 2019 SUs will not be released on public Download Center.
- SUs are released only if Critical or Important security issues are discovered in the product. We will confirm with ESU participants each Patch Tuesday whether an SU was provided or not.
- This Period 2 ESU will be valid for 6 months only (from May through October, 2026).
FAQs
Why does Microsoft require an additional purchase for Period 2 of this ESU if our organization already has the original SfB Server ESU?
The first period was priced appropriately for a 6-month program, so a second 6-month period must be purchased separately.
How are SfB Server ESU updates distributed?
Updates released under Period 2 SfB ESU will follow the same process as updates released under the original ESU program: Once enrolled, your organization will be provided information on how to access any ESU updates released during Period 2.
Our organization has Microsoft Volume Licensing. Do we get the SfB ESU automatically?
No. The SfB ESU program is a separate contract that each organization must explicitly purchase via their Microsoft account team.
Help! We purchased the ESU (original or Period 2) – but we do not know how to access the updates!
If you have already purchased the ESU and need information on accessing the latest Security Updates, please contact us by sending an email to ExchangeandSfBServerESUInquiry@service.microsoft.com.
A similar program is available for our Exchange Server customers. Please read more here: Announcing Period 2 Exchange 2016/2019 Extended Security Update (ESU) program
The Skype for Business Server Team
Microsoft