If you’re visiting London and on O2 you might want to take note – the network has just announced it's starting to offer WiFi at tube stations around London. It’s a result of a partnership with Virgin Media, which has set up WiFi for over 120 tube stations. Virgin Mobile is also in ties with EE and Vodafone so it’s an obvious decision by O2 to remain completive.
To get the service you’ll have to register your device. You’ll need to be on O2 (obviously) and if you’re on a contract you’ll get it free of charge. On pay-as-you-go (like prepaid in America) you have to buy a pass. These are incredibly expensive - £2/day, £5/week, and £15/month. So if you’re intending to use the service all the time you might want to consider moving to a contract (starting at £10/month) just to avoid this charge.
Because the underground is, well, underground, it’s unable to get cellular data reception. This means that WiFi hotspots are a must-have for data hungry commuters.
The only U.K. network to not sign up to offer WiFi on the Tube via Virgin is Three. This is the smallest network so this might be quite a damaging blow for them.