Created by O2's parent company Telefónica, Tu Me is a VoIP app and rival to Skype and Apple's own iMessage. Calls, texts and media messages are free, sent via Wi-Fi or your data plan instead of your contract's calling minutes and text message allowance.
You can store all your messages, conversations and interactions in a handy timeline format, which you can see in a browser as well as through the app in your phone. All your conversations are stored in the cloud rather than on your phone, so you won't lose them even if you lose your phone. Cloud storage is free for the first year but you'll start being charged for it after twelve months.
You don't have to be on O2 to take advantage of the app, and neither do the people you're calling or chatting with.
It's a new wheeze for phone networks to offer free calls -- their business model has generally been to keep you calling and texting and charge you for those. But the networks have realised that they can wring more money out of data.
Some networks, including Three and T-Mobile, offer unlimited data, but at a premium. If like most of us you don't have unlimited data then going over your allowance can cost you serious money -- so know your limits.
It's another example of an app that arrives on Apple's iOS devices first, but O2 promises Tu Me will launch for Android users and other platforms at some stage.
There are loads of VoIP apps knocking about of course, but O2 reckons Tu Me is the only one-stop shop. The network claims that Tu Me is "the only app that lets you make calls, send voice messages, instant messages, photos and location from one control within one screen, with no need to switch apps or tabs."
Have you found a great app that does all those things, or will you be using Tu Me? Let me know your thoughts in the comments or on our Facebook page.