O2 users in the UK now can make calls & send SMS from various London Underground stations. O2 has recently joined the London Underground WiFi network provided by Virgin Media. For them who doesn’t know yet, there is no mobile network signal inside most of the tube stations in London. Basically most of them are under the ground. No network signal, thus no phone calls or SMS.
[How-to] Free London Tube WiFi – Virgin Media, EE, Vodafone & O2 Customers Only
London Underground, the fastest and easiest way to travel across London. The service started 150 years ago. Alternatively commuters call “Tube” which describes it best. Most of the Underground or Tube stations are under the ground with no mobile phone network or internet access. Virgin Media brought WiFi to London Underground stations last year. Still the tube WiFi broadband internet access is not available at all stations of London Underground.