If you have a mobile phone, and it claims you have Internet service on it, you may not.

Mobile service providers have become increasingly aggressive in stopping access to services and sites they don't like, writes DeWayne Hendrick.

This is especially true for Vodafone, which owns half of Verizon Wireless of the U.S. (Verizon, in turn, has been the most aggressive in pursuing the "Walled Garden" approach here.)

According to DeWayne, Vodafone has summarily blocked access to all Voice over IP services, and even the main page of Skype, a VOIP procider. In the UK Vodafone is blocking access to all content that isn't "Vodafone-approved." (Translation: anything that might lose money for Vodafone.)

DeWayne notes that this is happening against a backdrop of dual mode WiFi headsets. But who's to say what those headsets may or may not permit? T-Mobile and Verizon both own paid WiFi hotspot networks. How much do you want to bet that, if they sell such phones, they're only going to allow WiFi VOIP access through those networks?