TELSTRA’S horror start to 2016 looks set to continue, with thousands of its customers claiming to be involved in a mobile billing “scam”.

While not technically illegal, the process known as third-party billing, involves mobile customers mistakenly joining subscription services by simply clicking on an advertisement or web page.

The common practice is used by all three major telcos, as part of a commercial agreement with the subscription service providers.

While Optus and Vodafone have a “double click opt-in” method, which asks customers twice before subscribing them, Telstra is the only telco still using a “one click opt-in” process.

This means customers are automatically subscribed when clicking on a banner or website.

The simplicity of joining these services has led to a 30 per cent increase in complaints to the Telecommunications Industry Ombudsman, with nearly 2000 customers unhappy with the telco.

According to a telco insider, the reason Telstra would be hesitant to change the practice is the fact it has netted millions of dollars in revenue from the dodgy practice.

“The one-click process had netted Telstra multimillion-dollar windfalls, with the telco getting about 30 per cent of revenues from each subscription,” the insider told The West Australian.

A quick perusal of Telstra’s crowd support portal shows literally hundreds of examples of customers being caught out in the scam.

“I have been charged $65.25 for ‘Third party purchases’ from ‘Openmarket Pty. Ltd’. These charges were for me receiving 14 text messages from a company I did not know or request any service from,” wrote one customer.

“Back in January I had a similar experience with ‘third party’ purchases on my Telstra mobile bill. After a lot of phone calls and follow-up emails, MIA Ltd/KKO Store refunded my money in late May. I still think Telstra has a lot to answer for in allowing companies like MIA access to their customers’ accounts. When I signed up for a mobile phone contract I contracted with *Telstra* for services, not MIA Ltd,” wrote another.

In addition to the annoyance of joining these services, many customers complain about the difficulty in opting out of these subscriptions.

Julie Davies and her husband Dave claimed to have been caught in the scam after receiving a text saying they had joined German company Jamster for $30.76.

“We have no idea how it happened. After we saw it we made three phone calls,” she said.

“Three times they said they had unsubscribed us, and then we got another bill. And you get charged for calling and texting.”

While the telco eventually reimbursed the couple, Ms Davies wonders why it happened to begin with.

“How can they do this? For us, it’s fraud,” she said.

Telstra told news.com.au direct carrier billing was a common industry practice.

“We don’t market or develop these services, but we allow our customers to charge content available on these sites to their mobile bill for convenience,” a spokeman said.

The telco said it enforces a number of consumer safeguards so that third party content providers follow mandatory policies and industry rules around advertising, promotion, pricing, opt out, purchase process and adequate customer care.

“We, along with the mobile industry, engage an independent monitoring service to ensure compliance of these policies and guidelines and to protect our customers,” the spokesman said.

“Third-party service providers are required to clearly present customers pricing information at point of purchase. Once a customer subscribes, the service provider must send the customer a confirmation SMS describing the service, the costs and the opt-out process.

“The third party service provider then sends the customer a reminder message every week that includes details of the costs and on how to opt out.”

In addition to monitoring these services, Telstra said it also provides customers with options to manage third-party charges on their bill.

“We apply a monthly spend limit on these services by default and customers can contact us to bar premium mobile services on their mobile number to restrict future access,” the spokesman said.

“We recognise that some customers have had a poor experience with these types of services. To help address this, we are in discussions with service providers about introducing a double opt-in process for subscriptions to help further safeguard customers from unwanted subscriptions charges.”

Telstra said if a customer has a concern about a third-party purchase on their bill, they should contact the third-party service provider’s customer helpline, in accordance with the complaint handling procedures regulated under the ‘Mobile Premium Services Code’.

“If a customer is not able to reach a third-party provider’s helpline or is not satisfied with their service, we can provide assistance and facilitate refunds working back with the provider,” the spokesman said.

The news comes after Telstra, suffered two national outages to its mobile phone network in February and March this year.

Telstra compensated customers with two days of “free data”, although its network delivered a slow experience for some users on the second occasion.

The man dubbed the “Telstra data guy” downloaded $10,000 worth of free data during Telstra’s Free Data Sunday and copped it from the rest of the country for abusing the system.

The telecommunications giant also copped heat on social media after it said it would no longer actively back marriage equality. It then had a change of heart over the issue — less than a week after it declared it was backing away from it.