To activate Microsoft Windows by Phone method, follow the guide below:1 – To enter/change your product key within Windows 10, follow the screenshot below. (Start > Settings > Update & Security > Activation > Change product key)2 – You will be prompted to enter product key. Enter your product key purchased. Then, click “Next”.3 – After entering the product key, you will receive the following error code 0x803F7001.4 – Press Windows logo key + R key to open Run, then type: SLUI 4, then click OK. (Note that there is a gap between SLUI and 4).5 – Select your country or region, then click Next.5 – An Installation ID will be generated. (In our example we got 9 groups of 7 numbers).7 – Go to https://cid.keyforest.net8 – Enter the Installation ID and click “Get Confirmation ID”.9 – You well get the Confirmation ID.10 – After obtaining the confirmation ID (CID). Click “Enter Confirmation ID” in the activation pop-up window.11 – Copy and past it group by group in the activation pop-up window Then, click “Activate Windows”.10 – If your product key is valid and the numbers have been entered correctly, You’re done, Windows is successfully activated.