Virgin Media's wireless broadband network on the London Underground will only be free to everyone for another week.
The broadband provider is scheduled to start charging non-customers for Wi-Fi access on the Tube from February.
"Until the end of January 2013 we're giving everyone full internet access for free. After that, full internet access will only be available for no extra cost to customers of Virgin Media and selected providers, or available to buy as Wi-Fi passes," the firm explained.
A message posted by the broadband provider on Twitter this week confirmed the Wi-Fi service - launched for the London 2012 Olympic and Paralympic Games - is "changing".
So far, Virgin Media has activated wireless broadband at 92 subterranean stations across the capital.
"We're working to get as many stations Wi-Fi ready as quickly as we can," the firm noted.
"You'll know when you're in an enabled station because you'll see the Wi-Fi logo in the ticket hall and around the station."