Over five million people have already downloaded the new version of the Skype app to their iPhones after just four days on the App Store, according to its developer.
Skype 2.0 arrived last week, bringing with it the ability to make Skype-to-Skype calls using the iPhone's 3G connection.
Skype said that the reason for this high figure is that it includes people who had already downloaded the original Skype app but were updating to the latest edition, as well as new users receiving it for the first time.
The popularity of the Skype app since its 3G capabilities were added is seen by some as an indication of the general hunger for VoIP calling over smartphones, perhaps heralding an end to the more traditional methods of voice communication.
In the US, the arrival of Skype 2.0 with 3G calling is being greeted by the networks with apprehension, as increased data usage is likely to ensue. Some, including AT&T, have decided to get rid of unlimited data tariffs altogether and it would not be surprising to see UK networks following suit.