A new app called Tu Go, developed by Telefonica for O2, may be rough around the ages, but still ranks as one of the most promising pieces of software we've seen come from a wireless provider. Available now for iOS and Android, the app lets O2 UK customers use their mobile number with any other iOS or Android device they own — so long as it has Wi-Fi, of course. Once installed and authenticated, you'll be able to place voice calls and send text messages from Tu Go, just as you would on your primary smartphone.

This offers a bit more utility (and convenience) compared with popular third-party messaging apps like WhatsApp and Kik, which require you to set up a new account independent of your mobile number. Obviously carriers would like to push back against that trend, and Telefonica is making a noble effort here. Unfortunately there is one negative: since you're using your actual phone number across those other devices, Telefonica has seen fit to draw from your O2 mobile minutes and SMS allotment — even though you're using the service via Wi-Fi. Assuming you can put up with that hurdle, Tu Go is available in the App Store and Google Play now.