April 2, 2009
If Skype was allowed to transmit voice calls over a cell data network, for several reasons, it would be unusable. There’s overhead in buffering and accommodating the effects of cellular data service in order to provide reasonable voice quality. Whereas IP packets and browsers don’t care if there is a slight delay, voice has stricter latency requirements and that’s one reason cell phone networks didn’t start out as data networks to begin with! Triangulation, echo cancellation, and multiplexing are systems that IP isn’t built for and even if it was, it would be like powering a computer with a solar panel that’s fed by a light bulb, plugged into the power grid.
If you’d like an example, get a 3g laptop card and open Skype on your laptop, then try and hold a phone call as a passenger traveling in a vehicle at 55mph; you’ll soon be disconnected or be unable to understand the call. Skype and the Internet it runs over has no idea you’re switching from Cell Tower 5 to Cell Tower 14 and to expect parts of the call in a different order from the different towers; even if it did, the towers aren’t aware of skype and the bandwidth overhead for the towers to communicate between Skype’s system and your cell phone would be excessive and negatively impact the network as a whole. ATT isn’t handicapping anybody, it’s just not that simple.
I can understand consumer advocacy but some things just don’t work. If it was really practical to run VoIPoCell then none of us would have Cell phones. Skype’s best effort would be to find a carrier to work with them at a higher level than just the iPhone; if Skype wants you to seamlessly transfer your call between the most efficient network, they’ll need much more than Apple’s cooperation.