Don't know about Microsoft, but I have a suspicion that the overseas-based call centres of some tel-co/internet suppliers might be selling info. I had an issue with my service, so I rang tech support ... over a day or so we managed to sort it out (would have been much quicker and easier had I been able to understand the "techie", though!).
Within three days, I got one of those phone calls, supposedly from Microsoft!
Seems reasonable enough to assume, doesn't it?