Notice: Each product key is licensed for one device only. Do not share or resell.

Activation Guide

Step-by-step instructions to activate your Microsoft Windows or Office product key purchased from RedTrex Technologies.

Info Most Microsoft product keys activate automatically online. Some keys may require activation through the official Microsoft Activation Portal — if your key does not activate automatically, please use the MS Activation Portal tab below.
Windows

Activate Windows 10 / 11

OEM & Retail
  1. 1
    Open Windows Settings

    Press Win + I to open Settings, then go to System → Activation.

  2. 2
    Click "Change product key"

    Under the Activation section, click Change product key (you may need admin permission).

  3. 3
    Enter your 25-character key

    Type the product key you received from RedTrex in the format:

    XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
  4. 4
    Click "Next" and then "Activate"

    Windows will connect to Microsoft servers and verify your key. Ensure you are connected to the internet.

  5. 5
    Activation complete

    You should see "Windows is activated" confirmation. Your copy is now genuine and licensed.

Success After activation, Windows Update will work fully and the "Activate Windows" watermark will disappear.
Alternative Method
Command Prompt

Activate via Command Prompt

Advanced
  1. 1
    Open Command Prompt as Administrator

    Press Win + S, type cmd, right-click and select Run as administrator.

  2. 2
    Enter your product key

    Type the following command and press Enter (replace with your actual key):

    slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
  3. 3
    Activate online

    Then run this command to connect to Microsoft and activate:

    slmgr /ato
  4. 4
    Check activation status

    Optionally confirm activation with:

    slmgr /xpr
Warning If activation fails with error 0xC004F074, your PC may be offline or blocked by a firewall. Try again with a stable internet connection or contact our support.
Troubleshooting
Command Prompt

Windows 11 Phone Activation Fix

Legacy UI Missing
⚠️ Some newer builds of Windows 11 (including 24H2 / 25H2) no longer display the classic blue phone activation window (slui 4). Instead, Windows may redirect to the modern Settings app and show:

"Can't activate via phone. Contact your administrator."

This is caused by Microsoft deprecating the legacy activation interface on newer builds.

If you already have your Confirmation ID from Microsoft phone activation, you can manually apply it using Command Prompt.

  1. 1
    Open Command Prompt as Administrator

    Press Start, search for CMD, right-click Command Prompt and select Run as administrator.

  2. 2
    Apply your Confirmation ID

    Run the following command, replacing YOUR-CONFIRMATION-ID with the ID provided by Microsoft:

    slmgr /atp YOUR-CONFIRMATION-ID

    Example:

    slmgr /atp 123456-123456-123456-123456-123456-123456-123456-123456
  3. 3
    Finalize Activation

    Run the following command to complete the activation process:

    slmgr /ato
  4. 4
    Verify Activation Status

    Confirm activation was successful by running:

    slmgr /xpr

    If successful, Windows will display: "The machine is permanently activated."

Note Additional Notes:
• This issue mainly affects newer Windows 11 builds where Microsoft deprecated the legacy activation wizard.
• The activation backend still functions normally even if the old UI is unavailable.
• This method works only with valid Confirmation IDs obtained through official Microsoft phone activation.
Office

Activate Microsoft Office 2021 / 2024

OEM & Retail
  1. 1
    Install Microsoft Office

    Download and install Office from the official Microsoft website if you haven't already. Use your RedTrex key during or after installation.

  2. 2
    Open any Office application

    Launch Word, Excel, PowerPoint, or any Office app. You will be prompted to activate or sign in.

  3. 3
    Choose "Enter a product key instead"

    On the activation screen, select the option to enter a product key rather than signing in with a Microsoft account.

  4. 4
    Enter your 25-character product key

    Type the key you received from RedTrex in the format:

    XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
  5. 5
    Follow the on-screen prompts

    Click Next and allow Office to verify the key with Microsoft servers. Ensure you are connected to the internet.

  6. 6
    Activation complete

    Once verified, you will see the "Activation successful" message. Office is now fully licensed on your device.

Success All Office apps (Word, Excel, PowerPoint, Outlook, etc.) will unlock immediately after successful activation.
Phone Activation (Offline)
Phone

Activate Office by Phone

Offline Method
  1. 1
    Open the Activation Wizard

    Open an Office app → File → Account → Activate Product, then choose I want to activate the software by telephone.

  2. 2
    Select your country

    Select Sri Lanka or your country from the dropdown. A Microsoft phone number will be displayed.

  3. 3
    Call the Microsoft number

    Call the number shown. An automated system will ask for the Installation ID displayed on screen.

  4. 4
    Enter the Confirmation ID

    The system will provide a Confirmation ID. Enter it in the activation wizard to complete activation.

Tip Phone activation is useful when your PC has no internet access or online activation keeps failing. It works 24/7 through Microsoft's automated system.
Office 365 / Microsoft 365
Microsoft 365

Microsoft 365 — Pre-Activated Account

Account Login
  1. 1
    Receive your account credentials from RedTrex

    After purchase, you will receive a Microsoft 365 email address and a temporary password from RedTrex Technologies. Your account is already activated and ready to use.

  2. 2
    Sign in at Microsoft 365

    Go to microsoft365.com in your browser and click Sign in. Enter the email and temporary password provided by RedTrex.

  3. 3
    Change your password on first login

    You will be prompted to set a new password immediately. Choose a strong, unique password and save it securely. This is required before you can access your account.

  4. 4
    Access your Microsoft 365 apps

    Once signed in, you can use Office apps directly in the browser or download and install them on your device from your Microsoft 365 account dashboard.

Warning Important: The email address of your account cannot be changed. Only the password can be updated. Keep your credentials safe — do not share your password with anyone.
Success No product key is needed. Your Microsoft 365 subscription is already active — simply sign in and start using it.
Key

Microsoft Product Activation Portal

Use the official Microsoft Activation Portal to activate your product key directly through Microsoft's servers. You must agree to the licensing terms before accessing the portal.

Open Activation Portal →
Checklist

Before You Use the Portal

  1. 1
    Have your product key ready

    Keep the 25-character key from your RedTrex purchase accessible. You will need it during the activation process.

  2. 2
    Read and agree to the licensing terms

    Each key is licensed for a single device only. You must accept the terms on the portal page before proceeding.

  3. 3
    Click "Activation Portal" to proceed

    After agreeing, you will be taken to Microsoft's official activation server. Follow the instructions there to complete activation.

  4. 4
    Contact support if needed

    If activation fails, contact our support team via WhatsApp for assistance within 24 hours.

Warning Important: Reusing, sharing, or reselling a product key violates Microsoft licensing terms and Redtrex's reseller policy. Misuse may result in immediate license deactivation with no refund or replacement.
Support

Need Help Activating?

WhatsApp
WhatsApp Support

Message us directly for fast activation help — available 7 days a week.

Chat on WhatsApp →
Web
Customer Portal

Log in to the Zoho customer portal to view your order history

Customer Portal →