A little Vonage blockage?

Is Vonage being blocked by its competition? Vonage has reportedly filed a complaint with the FCC that competitors—reportedly rural Local Exchange Carriers (basically small local telephone companies)—have been blocking users of its broadband VoIP service from completing calls to some numbers. There's already been plenty of speculation that an ISP trying to sell its own VoIP service might block the ports Vonage and other VoIP providers use to make calls, but this sounds like it's a little different, and that the blowback is coming from rural carriers who are worried about losing subscribers to VoIP.

[Via GigaOm]