Volume License Key. Keys Microsoft sells to businesses in high quantities. In the past those special keys didn't require activation. They could be used to install XP Pro 32 and 64 bit and also Office 2003, 2007 and don't require activation at all. I merely mentioned that in this day an age. Why would anyone bother activating XP using phone? When you can use a VLK iso and key. Microsoft won't care about XP at this point.
In the case of vista and 7 and 8 yes you can use phone activation and it works. With windows 10 as well. I heard there was a limit of how many times you could activate the same key. If you used it too often then you had to call a live MS representative to help you out. That's what I heard. Also if I remember correctly after some window 10 update you have to activate online now. Windows 11 is only online now as well.