As of Tuesday afternoon, 73 stations have Wi-Fi available. Archway, Seven Sisters and Swiss Cottage should go live soon, according to Virgin.
The telecoms provider has been having talks with mobile operators and ISPs for them to resell service on the Tube's Wi-Fi network at the end of the summer, the company said.
"We're speaking to a range of potential wholesale partners, including mobile operators, ISPs and other service providers, about our new Wi-Fi service on London Underground. We want to make Wi-Fi on London Underground widely available, with a wholesale model combining the best consumer experience with real choice," a Virgin Media spokesman told ZDNet.
The company competes in mobile with O2, Three, Orange, T-Mobile and Vodafone, among others. If it can get operators on board, the service would run on top of Virgin Media's network, though customers would see their usual operator name on their devices.
If another operator decides to resell the services, it's likely that the additional feature will be bundled with existing products. Virgin hopes to have at least one wholesale partner on board before the end of 2012.
The London Underground service is free to everyone for the summer, during the Olympic Games. After that it will come at no extra cost to existing Virgin Media customers, while others can get it on a pay-as-you-go basis. Access to the Tube Wi-Fi splash portal, which provides information about the London Underground services, is expected to remain free to all.
Virgin has not yet said how much pay-as-you-go access will cost. It plans to have switched on Wi-Fi in 120 London Underground stations before the end of 2012.