O2 has unveiled its TU Go service to enable Pay Monthly contract customers to make and receive calls and text messages on a range of devices - including tablets - rather than being tied to their O2 handset.

TU Go is a free app that allows customers to use their existing O2 bundle of call time and text message allowances on multiple devices, including making VoIP calls over the internet.

The service uses a customer’s existing O2 number on all devices so there are no extra usernames to remember and no separate numbers to give out to contacts. Customers using TU Go can make and receive calls and texts to and from anyone on any network, even if the recipient doesn’t have the app installed.

The TU Go app is available on Apple devices running iOS 5 and above, Android devices running Android 2.3.1 - "Gingerbread" - and above, and PCs running Windows 7 only.

Sally Cowdry, marketing and consumer director at O2 in the UK, said: “TU Go lets you take a call on a tablet, pick up text messages on a PC and have conversations in places with Wi-Fi coverage but no mobile signal."

When a user receives a call, their TU Go app will ring across all the devices it is installed on. A text message will show just the same as it would on a laptop as it would on their phone. Users are also able to access their device’s local address books and see all their conversations and call history in one timeline, synced across all devices.

Users can log into the app on up to five devices simultaneously. As yet, the service is not available on O2 business contracts, although it is believed O2 is planning to widen the service's availability.