"Three inTouch
Sometimes it can be hard to get a good signal when you’re indoors. We know that and we want to help.
Imagine if you could call and text even if you didn’t have signal?
Well that’s exactly what Three inTouch allows you to do. It’s an amazing app that lets you make calls and texts over Wi-Fi when you don’t have signal. Yes, you read that right.
Sounds pretty awesome doesn’t it? All you need to do is download the app (it’s free, of course), connect to our 3G or 4G network to activate it and then you’re good to go.
You can use inTouch wherever there is Wi-Fi but no 3G or 4G signal. So we hope for a lot of you, this means at home or at work, where you might previously have had difficulties making calls or sending texts. Hoorah!
And with the recent introduction of Wi-Fi on the London Underground, you know what this means don’t you? Yep, you’ll be able to make a call whilst on an underground platform. Which is sure to draw attention from fellow commuters!
InTouch is available now for Android and iOS."
http://blog.three.co.uk/2014/07/30/three-intouch/