Commuters travelling through Melbourne's City Loop can now text, chat and stream content over the internet as mobile coverage becomes available in the tunnels.

Passengers have access to 3G voice and 4G data coverage through the 12 kilometre stretch of train tunnels.

Key points: Mobile phone and data coverage now available in City Loop

Mobile phone and data coverage now available in City Loop Commuters have access to 3G voice and 4G data network

Commuters have access to 3G voice and 4G data network Work being conducted to improve 4G speeds

The city's underground stations have had phone coverage for about 15 years but the tunnels connecting them have been blackspots for mobile and internet coverage.

"This ends years of frustration for passengers, who would be in the middle of a conversation only for their phone to cut out when they entered the loop," Public Transport Minister Jacinta Allen said in a statement.

"Passengers can now text, talk and stream from their phones or tablets anywhere in the city loop.

"When the Melbourne loop was opened 30 years ago, mobile phones were just a twinkle in someone's eye.

"Technology has made great advances."

Over the past few months, commuters have been reporting patchy connections in the loop, as telecommunications authorities tested new signals.

In recent days, the connection has become much more consistent.

The Victorian Government announced in June last year that a deal had been reached with rail authorities and telecommunications companies to deliver the service.

It said 3G services would be available on the City Loop by the end of 2014 and 4G services would be running by the end of 2015.

But complications with the driver communications systems forced the delay of the roll-out.

Ms Allen said work would be done over the next year to improve the 4G data service.

"That will see increased capacity and data speeds as passengers now enjoy, for the first time, the ability to connect through their smartphone to the rest of the world as they travel through the City Loop," she said.

Telcos urged to identify blackspots

Daniel Bowen of the Public Transport Users Association said he was surprised by how long it took to get coverage in the loop.

"But I guess better late than never," he said.

Mr Bowen urged telecommunications companies to now look at other blackspots across the public transport network.

"There's certainly areas on some lines where trains will go under roads, for instance, where you lose signal," he said.

"There's phone network congestion in peak hour when a lot of people are trying to use it.

Mr Bowen said there were many blackspots along Victoria's regional train network, V/Line, that needed to be addressed.

VicTrack chief executive Campbell Rose said he was confident testing had ironed out any problems.

"There may be a drop-out or two somewhere along the line, but no, the system works," he said.

"We've been testing it, and I don't think we've had any complaints."

Mr Rose said VicTrack would work to enhance the capacity of the 4G network to keep up with rapid advances in technology.

"When the MURL (Melbourne Underground Rail Loop) was built, it was never envisaged that we'd use mobile telephones as we do today, let alone stream something from Netflix," he said.

"What we need to do is ensure the capacity of the system keeps up with the ability to be able to draw down larger and larger packets of data."

Optus spokesman David Epstein said the transition into the tunnels should be seamless for mobile phone users.

"You'll be able to talk, text, watch and listen to your heart's content right through the rail link," he said.

Passengers travelling through the loop this morning have reported generally good coverage.

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