I'm considering using Skype only for my calls on iPhone. Now that most carriers (in the UK anyway) don't provide unlimited data, and the iPhone can handle Skype with multitasking, are there any metrics on how much data a typical call uses?
How much bandwidth does a Skype call use?
bandwidth;skype for web
Between 30 and 70 kbps, according to this thread on their official forum: http://forum.skype.com/index.php?showtopic=32510