For more than twenty years, activating Windows or Office without an internet connection meant calling a Microsoft automated phone line. That is no longer the case. On 3 December 2025 Microsoft retired the automated telephone system and replaced it with a web portal. Offline activation itself still works. Here is the up-to-date procedure.
What changed at the end of 2025
- The automated line that read out the confirmation ID no longer exists.
- Microsoft now directs users to an online activation portal, which issues the same confirmation ID.
- Microsoft’s own documentation is explicit: if an activation phone number still appears in the wizard, do not call it.
- The principle is unchanged: the machine being activated still does not need to be online. Only the device you use to open the portal does.
When you need this method
Three situations call for it:
- a computer with no internet access, deliberately isolated or sitting on a closed network;
- a reactivation that fails online after a hardware change;
- so-called “phone activation” keys, sold for less precisely because they require this extra step.
Step by step
- Enter the key as usual. For Windows: Settings › System › Activation › Change product key. For Office: the activation wizard that appears the first time you launch an application.
- Get the installation ID. If online activation does not go through, the Activation page offers phone or automated activation. The wizard then displays the installation ID, a long string of digits split into nine blocks. From an elevated command prompt,
slmgr /dtireturns the same identifier. - Open the Microsoft activation portal from any connected device — another computer, a tablet, a phone: aka.ms/WindowsActivate. The portal asks you to pass a CAPTCHA and to sign in with a Microsoft account.
- Type in the installation ID exactly as displayed. A single wrong digit produces an invalid confirmation ID: this is the number one cause of failure.
- Enter the confirmation ID returned by the portal into the activation wizard. You can also use the command line:
slmgr /atp YOUR_CONFIRMATION_ID. - Check the result. The Activation page should report that Windows is activated. The command
slmgr /xprconfirms the licence status.
The legacy wizard is still reachable by running slui 4, but Microsoft notes that on recent builds of Windows 11 it may no longer behave as it used to. If that happens, use the slmgr commands above.
The Office case
The principle is the same: the Office activation wizard shows an installation ID, the Microsoft portal returns the confirmation ID, and you type it into the window you left open. Do not close the wizard between the two steps, otherwise a new installation ID is generated and the confirmation ID you obtained is no longer valid.
The most common mistakes
- Closing the activation wizard before entering the confirmation ID.
- Mistyping a digit: read the installation ID back block by block.
- Mixing up editions: a Pro key will not activate a Home installation, and vice versa.
- Calling the number shown on screen: the automated line has been switched off.
Phone activation keys in our catalogue
These licences are genuine and perpetual; they simply require the step described above at first activation. That is what explains their lower price.
- Office 2021 Pro Plus – retail key, phone activation
- Office 2019 Pro Plus – retail key, phone activation
- Office 2016 Professional Plus – phone activation key
If you would rather activate online with no extra steps, pick a standard retail key in the Microsoft Windows or Microsoft Office categories. The difference between the licence types is set out in our guide OEM or retail key.
Need help during activation?
Write to us at support@chkey.ch with your order number and, if you can, a photo of the error message. We will walk you through the activation step by step. Replacement terms are set out in our FAQ and on the Shipping & Returns page.