O2 announced that it’s the latest mobile operator in the UK to offer customers free Wi-Fi access on the London Underground, joining EE, Virgin Media, and Vodafone. Any users with an existing O2 contract who also have O2 WiFi service will automatically be registered for the service. More interestingly, O2 WiFi is a free app that’s available both in Google Play and the App Store, which means that the possibility exists that the first universally free WiFi might be activated when O2 launches their service. Customers will be able to use the service on up to five devices simultaneously, as well as WiFi-only devices. WIth O2’s service, only one network operator won’t offer WiFi for free in the Tube – it remains to be seen if this service will come across the pond anytime soon.