Microsoft Extends Skype for Business ESU Program with "Period 2" Option

Microsoft has announced a "Period 2" extension for the Skype for Business Server 2015 and 2019 Extended Security Update (ESU) program, providing organizations with an additional six months of critical security updates through October 2026. This move comes as many enterprises face challenges completing their migration to Skype for Business Server Subscription Edition or Microsoft Teams before the original ESU program concludes at the end of April 2026.

Understanding the ESU Extension

The original ESU program, which began in October 2025, was designed to bridge the gap for organizations still running unsupported versions of Skype for Business Server. With the original program ending soon, Microsoft recognized that some customers would need more time to complete their migrations.

"Period 2" represents a distinct six-month window from May 1, 2026 through October 31, 2026. It's important to note that this is not an automatic extension of the existing program. Organizations must proactively purchase ESU coverage for this new period, even if they participated in the original ESU program.

Key Requirements and Process

Organizations interested in Period 2 ESU must:

• Re-purchase ESU coverage specifically for the May-October 2026 timeframe
• Contact their Microsoft account team for pricing and purchase details
• Follow new instructions provided after purchase to access security updates

Microsoft emphasizes that Period 2 is priced appropriately for a six-month program and must be purchased separately from the original ESU coverage. The company has also clarified that organizations do not need to have purchased Period 1 ESU to participate in Period 2.

Security Update Distribution

Security updates for Period 2 will follow the same distribution model as the original ESU program. Updates will be provided privately to enrolled organizations and will not be released publicly on the Microsoft Download Center. These updates will only be issued if Critical or Important security vulnerabilities are discovered in the product.

Organizations will receive confirmation each Patch Tuesday regarding whether security updates were provided for that month. The original ESU program instructions will not work for updates released after April 2026, making it essential for enrolled organizations to follow the new process.

Migration Considerations

While the ESU extension provides additional security coverage, Microsoft stresses that Skype for Business Server 2015 and 2019 remain out of support as of October 14, 2025. Organizations cannot open support cases for these versions unless directly related to issues with security updates released during the ESU period.

This extension gives organizations additional breathing room to complete migrations to supported platforms, whether that's Skype for Business Server Subscription Edition or Microsoft Teams. However, the clock is ticking, as Microsoft has confirmed there will be no further extensions beyond Period 2.

Similar Program for Exchange Server

Microsoft is offering a parallel ESU extension for Exchange Server 2016 and 2019 customers. Organizations running these versions can also enroll in a Period 2 ESU program, following similar terms and conditions.

Getting Started

Organizations ready to purchase Period 2 ESU should contact their Microsoft account team immediately to discuss pricing and begin the enrollment process. For those who have already purchased ESU but need assistance accessing updates, Microsoft provides support through [email protected].

The announcement reflects Microsoft's recognition of the complex migration challenges many enterprises face when moving from legacy communication platforms to modern solutions. While providing this extension, the company continues to encourage organizations to accelerate their migration plans to ensure they're on supported, secure platforms beyond October 2026.