How do you think Free got to be worth so much?
http://en.wikipedia.org/wiki/Communications_Assistance_for_L...
http://en.wikipedia.org/wiki/Lawful_interception
Microsoft's premise is that the techniques used for VoIP are different then traditional lawful interception, but I don't think anything described in the patent is non-obvious. Nonetheless, they will probably get it awarded, as more then 50% of patent applications do (forgot where I got the statistic from), and even more when its from large tech corporations that have dedicated in-house patent lawyers filing the patent applications.
When you think about it, the USPTO gets money from awarding patents and collects yearly fees through the 20-year life of a patent, and the army of patent examiners they have on staff do not come cheap (starting salaries range from 52-79k), and for the most part they are self-funded and do not rely on U.S. Congress money - so there is every incentive in the system for them to award every patent applied for.
No wonder they can't manage to hire engineers who know any of the many technologies that have been around for decades and still get repeatedly patented every week. That's as bad as the continuing prohibition on admitting computer engineers and software engineers to the patent bar while software becomes an ever larger fraction of the case load.
standard disclaimer: this does post does not constitute legal advice.
Besides, the patent was filed back in 2009, long before Microsoft acquisition in Skype.