Sydney rail travellers have benefited from mobile coverage in the North Sydney, Chatswood, and CBD North and Western Rail tunnels for almost a year.

Phase two of the project has now been completed, providing coverage throughout the City Circle.

Optus offers 2G, 3G and 4G coverage in the tunnels and on platforms, while Telstra customers get 3G and 4G coverage. Vodafone previously foreshadowed service throughout the City Circle but had not made an announcement at the time of writing.

"Adding network coverage in the City Circle tunnels is part of Telstra's ongoing commitment and investment to ensure more people get connected and stay connected," said Telstra director of network engineering Anthony Goonan.

Optus vice president of corporate and regulatory affairs David Epstein said "Sydneysiders travelling on one of the city's busiest train lines can access Optus 2G, 3G and 4G coverage on the platform and throughout the tunnels, making the daily commute more entertaining and productive."

Phase three of the project, scheduled for completion in early 2014, will provide coverage on the Eastern Suburbs line.

Image: NSW Transport