I think this year but I suggest you look it up yourself, they probably are mentioned in the court documents and the dates are public.

I can't find any specific dates (and I'm not going to go fishing into court documents), but wow, this has been going on for more than a decade now !

https://en.wikipedia.org/wiki/VirnetX

> Separately, in December 2014, Microsoft and VirnetX settled patent disputes over Skype technology for $23 million.