As expected, the UK gained its first "integrated" WiFi calling service last week courtesy of mobile giant EE. The surprise was that it first became available on a selection of iPhone models -- those being the iPhone 6, 6 Plus, 5S and 5C -- after Apple raced out a software upgrade supporting the new feature on April 8. Only a day earlier, EE had informed the industry the Lumia 640 and Samsung's Galaxy S6 would be its inaugural WiFi calling devices.