Microsoft is offering free Wi-Fi to train commuters via the existing Cloud Wi-Fi network.
The Microsoft branded Wi-Fi is being used by Redmond to help publicise its on-demand cloud-based Office 365 productivity suite.
Earlier this month it was announced that 225 London taxis would also be offering free Wi-Fi as part of a Microsoft campaign to publicise its business solutions. That connectivity is being enabled via the Vodafone network.
The Cloud already offers commuters 15 minutes of free Wi-Fi a day at selected Network Rail stations, but the Microsoft offering is now unlimited for a month-long period up to 24 April.
During the campaign users can access information about Microsoft Office 365 via a button in The Cloud's Content Portal.
Philippa Snare, chief marketing officer at Microsoft UK, said, "This campaign is designed to help commuters tap into new ways of working. The mobile workforce is constantly growing and so is the need to access mobile internet."