Remember AT&T's hilariously ironic request for the FCC to investigate Google Voice for not following net neutrality rules? The FCC is all over it, and has sent a letter to Google asking why and how Google Voice blocks certain calls.
The FCC's interested in part because some lawmakers jumped on its ass, but also because it's very interested in making some new rules for telecoms. Currently, Google Voice blocks calls to some rural carriers, conference call services and naughty talk lines because they have pricey access fees.
You can read the full letter here (PeeDeeEff), but basically the FCC asks Google to describe how calls are routed with Google Voice, how it decides what numbers to block, what exactly Google means by saying the service is "invitation-only", whether or not it plans to charge money for GV (!), and some other stuff.