You likely could get get a healthy debate going over which of the leading mobile providers is most 'open' to over the top mobile VoIP, and AT&T's apparent new decision to allow Skype to run on Apple iPhones will not settle the argument. The Skype 2.0 application will run without fees until 2011, when users will have to pay a still-to-be-determined fee for those calls. But AT&T appears not to be part of the direct revenue stream. Skype will set its own charges for SkyeOut rates, just as it does for similar SkypeOut or SkypeIn calls using PCs.

AT&T apparently believes it will benefit most by attracting more customers to use of its iPhones and data plans, and apparently does not want to be in the Skype voice ecosystem. Verizon, on the other hand, seems to be part of the value chain by funneling Skype calls from end points through its global voice network, a method that undoubtedly provides better quality on a sustained basis.

When Verizon announced it would support Skype, it continued to require that users purchase both a data and voice plan to use the VoIP service.

AT&T and Apple, on the other hand, simply stayed completely out of the Skype arena by barring use of the application on the 3G mobile network. But AT&T apparently now will allow Skype calls to use the mobile network, but without any apparent direct role in the voice revenue ecosystem. Consider the irony: no role when barring the app, and no direct revenue when allowing the app.

The difference appears to be a new assessment of the competitive environment and the role such access can play in making the AT&T iPhone experience more sticky and valuable than it might be on another network.

It probably is fair to say that both AT&T and Verizon Wireless are taking approaches that make voice revenue less important than the experience of using VoIP on their handsets and networks. What seems more important is the role such access can have in driving adoption of smartphones, using Skype and driving additional data plan revenues.

By Gary Kim.