The mobile operator has teamed up with Southern Trains and Nomad Systems, it said on Wednesday. Wi-Fi access points have been installed in Southern Trains' rolling stock, letting anyone travelling between Brighton and London with a Wi-Fi-enabled laptop or PDA get Internet access on the move.
A free trial of the service is due to begin in early March, ahead of a commercial launch planned for this summer.
Several other companies, such as Broadreach and Icomera, are already operating train Wi-Fi services in the UK. T-Mobile, though, claims that it is the first 'genuine broadband' service, because it uses WiMax as the uplink to the Internet.
WiMax gives T-Mobile a two-way connection of up to 32Mbps, which should be enough to support a large number of individual passengers accessing it at the same time.
"Although the London to Brighton line presents many challenges we have proved that high-speed wireless access to moving trains is possible without building huge towers or other costly infrastructure. Whether the train travels through tunnels, bridges or through high hedgerows, customers should not experience a drop in service," said Nigel Wallbridge, executive chairman of Nomad Digital, in a statement.
Broadreach's system uses a combination of 3G networks and a satellite link to connect back to the Internet.