GNER has said that half of its 41 trains now have Wi-Fi on-board so commuters can access the Internet.
When GNER began its current franchise in May 2005, it confirmed plans to install Wi-Fi across its fleet, following a successful trial onboard ten rebuilt "Mallard" trains.
Completion was due for May 2007, but in response to popular demand from passengers, GNER has speeded up the project and all of its trains will have Wi-Fi by August of this year - 9 months early.
GNER chief executive Christopher Garnett said: "We're delighted to have reached the halfway point in the rollout of wireless internet to our trains".
GNER trains send and receive communications signals via a combination of a roof-mounted satellite dish and mobile phone antenna using 3G and GPRS technology.
Each coach along the entire length of the train is then connected via the onboard wireless network to create a Wi-Fi 'hot-spot' throughout every coach on the train.
The new technology means passengers using Wi-Fi can remain connected throughout the journey, even in tunnels.
First Class passengers can access Wi-Fi free of charge during their journey, while in Standard Class the system operates on a "pay-as-you-go" principle.
Prices for Standard Class will be £2.95 for 30 minutes, £4.95 for 60 minutes £7.95 for 120 minutes and £9.95 for 3 hours.