People had to do a phone activation because the online activation didn't work anymore.

I had already addressed the issue of Microsoft Office 2010 activation within my German blog blog in 2017. Besides, not everyone wants this C2R technology on their machine (see Office: Instabilities/crashes due to C2R and MSI parallel installation?). And a Facebook user wrote that an activation with C2R still works – but I'm not sure if a key can be used for an MSI installation with Click-to-Run (C2R). It could also be a Linux-based KMS server, as I read on Facebook at a feedback to my German copy of this article. Notes: Activating a KMS key against a Key Management Server probably still works, as I interpret above tweet right.

So there, too, activation seems to be denied by Microsoft. Tobias answered that he uses a volume license with a multi-activation key (MAK) for his Microsoft Office 2010. German blog reader Karl says in the following reply tweet: No longer works. The German tweet above says, he could not activate Microsoft Office Professional Plus 2010, either online nor via telephone activation. German blog reader Tobias has now had the unpleasant experience that this required activation no longer works – neither the online activation, nor a telephone activation, as he shares on Twitter. The company has simply switched off the activation servers that are required for Office 2010 activation. Unfortunately, some users who bought Microsoft Office 2010, haven't calced without Microsoft. Should be no problem for a regular buyer who owns a key. To be able to use Microsoft Office 2010 after a new installation, it must be activated by Microsoft. Microsoft Office 2010 needs to be activated

Ms office activation failed