Life underground has grown more mobile-Internet friendly with Tokyo Metro Co.’s trial free Wi-Fi service expanding to effectively all of its subway stations at the start of the month.

By registering for an application called MANTA (Metro Amusement Network Trinity App), commuters can have their smartphone connected to the free Wi-Fi inside Tokyo Metro stations until July 31, when the trial will end.

There are some limitations, as people can access the service only five times a day and never for more than 15 minute per use.

A Tokyo Metro spokesman said the time limit is based on the expectation that most people will use the Wi-Fi service while waiting for their train.

The service is available in all Tokyo Metro stations except Wakoshi on the Fukutoshin and Yurakucho lines, Nakano and Nishifunabashi on the Tozai Line, Yoyogiuehara on the Chiyoda Line, Shibuya on the Fukutoshin and Hanzomon lines, Kitasenju on the Hibiya Line, and Meguro on the Nanboku Line, because different firms manage these stations.

Tokyo Metro and NTT Broadband Platform Inc. jointly launched the MANTA app and the free Wi-Fi on Feb. 14 at around 30 stations.

When accessing the Wi-Fi, MANTA provides various information regarding that station, such as train schedules and local area guides, as well as news.

The application is available for Google Android handsets and Apple iPhones and iPads through their app stores.

Tokyo Metro is putting the Wi-Fi router locations on station maps so users can try to get the strongest possible signal.

On top of the free Wi-Fi at the stations, the subway cellphone Internet network for 3G and LTE has also been reinforced recently.

The major cellphone carriers announced last month that mobile phone service was made available on all Tokyo Metro lines on March 21 and Toei Subway lines on March 27, meaning people can use the Internet when they are riding underground.

Before 2011, cellphone connections in subway tunnels were hardly available. But after the March 11, 2011, earthquake reinforced the risk of being stuck underground without Internet access, the carriers and subway operators accelerated their efforts.

Tokyo Metro said it will decide later whether to continue the free Wi-Fi service beyond July 31.