Commuters will be able to check emails on the Tube by the start of the London Olympics.
Transport for London (TFL) said a successful trial at Charing Cross meant wi-fi coverage would
eventually be installed on the whole Underground network.
Telecoms companies will now bid to set up the network with 120 stations to be ready for wi-fi by June 2012, with front-runners likely to be major UK telecoms companies 02, Orange, T-Mobile and Vodafone.
Orange said it and and the other three companies were all in discussions with London Underground.
"The four network operators are working together," an Orange spokesperson said.
"The mobile phone companies remain in discussions to explore mobile phone services for the London Underground in time for the Olympics."
02 also said it was in talks with TFL but would not comment further on the wi-fi network as it said it was "commercially confidential".
The Charing Cross project was carried out by BT Openzone.
Technology to allow mobile phones on the Underground is also being investigated.
Staff at 16 stations currently use wi-fi and it is this service that will be provided for passengers.
London Mayor Boris Johnson said: “Wi-fi technology will allow Londoners to use mobile devices to pick up emails, access social media sites and traverse with the world above.”
As well as helping commuters, wi-fi is a future source of revenue for London Underground.
A contract will be given to the chosen bidder by the end of this year.