How do I activate WindowsXP now that support has ended?

I found two solutions, both of them work offline, so you don't have to connect the WinXP system to a network (although I have to use WinXP I try to minimize security risks):

A) Activating over the phone

Calling the current MS activation number for a product still in support (e.g. for activation for Win7) and choosing "Other Products" in the voice menu. This is my preferred one since you don't have to tamper with the system. In my case (Nov 2019) I followed the link to the Microsoft Licensing Activation Centers worldwide telephone numbers.

B) Disabling activation process

Deleting the value of the OOBETimer key (HKEY_LOCAL_MACHINE/Software/Microsoft/Windows NT/CurrentVersion/WPAEvents/OOBETimer) and starting the activation via command prompt: msoobe /a. This will disable the activation requirement for good, but might cause issues (although I haven't found any yet) (source)

Side note: The number I used for Germany was +49 89 2444 5093 (checked Nov.2019) but I would suggest to look at the list provided through the link since those number will be updated. US number +1 888-571-2048 is suppose to work as well, but I didn't try it.

I managed to activate an XP license key using this link that I got off of a Microsoft support forum. I don't know how long this link will stay active, but as at posting date it still works.

UPDATE:

The link that I posted is not on the Microsoft site, but to the best of my knowledge it is what Microsoft uses for activation. It is referred to as Microsoft's "Self Service for Mobile".

This link just allows you to manually activate the the installation. So you select activate via phone option, then your XP box activation screen will give you a set of numbers. You enter these numbers into the site and the site gives you the response numbers to enter into the XP installation that you are needing to activate. Then you click on "next" and the activation completes.

So there is no way that this could contain malware or virus's because nothing is installed or run on the box that you are activating, unlike the other options listed here that involve running scripts to by-pass the activation process.

I am just giving my experience here; I had a box belonging to a friend of mine that somehow got into an activation loop (even though it had previously been activated for years), and I got the PC activated using the link. And I did so by following the standard Microsoft activation screens.

I also gave the link to the Microsoft forum where I found this link, but, yes, disclaimer: use at your own discretion.

Regarding failure of online activation, did you check the date on the system?

I activated Windows XP on an old machine one week ago.

After two days of trying to figure out why almost everything Internet-related was not working (browsing, windows update, activation), it turns out the date was wrong and set to 2004.

A wildly wrong date will break anything that uses ssl/tls, as certificates will be assumed to be either expired (if the date is in the future) or not yet valid (if the date is in the past). This apparently includes windows activation.

I changed it to the current date & time and was able to activate and update the OS.

So, try this .bat script to do this process. Due to the limit size (3.9mb) for .gif files, link for viewers here.

This .bat script will do it.

@echo off && cd /d "."
rem :: the windows reg key used to activate process in this bat/cmd read/write/delete ::  
set "_wpaKey=HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\WPAEvents"

reg query  "%_WPAKey%" | find /i "OOBETimer"                & rem/ output key value in screen
reg export "%_WPAKey%" ".\PAEvents_SAVE_Original.Reg"       & rem/ save original value in file
reg delete "%_WPAKey%" /v "OOBETimer" /f >nul               & rem/ remove the key/value
reg add    "%_wpaKey%" /v OOBETimer /t REG_BINARY /f        & rem/ recreate the key/value
timeout /t -1 2> nul                                        & rem/ time out to see the results
cd /d "C:\WINDOWS\system32\oobe"                            & rem/ goto to drive/folder C:\WINDOWS\system32\oobe\
start "" /realtime C:\WINDOWS\system32\oobe\msoobe.exe /a   & rem/ start the activate windows interface 
echo/:: sample key !! --^>  ISAY-REIN-STAT-EMO-NICA^!       & rem/ if need put some windows key to view/copy/paste   
pause >nul                                                  & rem/ pause to keep console windows