A father in B.C. was surprised to learn his son had incurred hundreds of dollars in text message fees despite an apparently unlimited plan, another example of so-called "bill shock."

The term refers to racking up huge charges, sometimes in the thousands of dollars, for using a smartphone in seemingly innocuous ways.

In that case the man's teenaged son had replied to text messages sent by his girlfriend – who lived nearby – using a "free" messaging service that was based in the U.S.

However, consumers can also end up owing service providers huge sums for inadvertently going over their data usage, allowing children to purchase in-game upgrades for real-world dollars or using their devices in foreign countries.

For Howard Maker, who was appointed Canada's first commissioner for complaints for telecommunications services in August 2008, it is often matter of understanding both your own phone plan and the way the given applications use your device.

"My view always is an informed consumer is always more likely to make good decisions," he said.

CBC News spoke to a number of telecommunication experts to come up with four ways to help avoid "bill shock."

1. Understand the app

One of the first lines of defence against incurring a huge bill is to understand how an application operates and often this means reading both the description displayed on your phone before you download it as well as its longer service agreement, said David Fewer, a director with the Canadian Internet Policy and Public Interest Clinic at the University of Ottawa.

This information should contain whether there are any additional charges down the road and how the app interfaces with your phone, although the language can often be confusing if not completely undecipherable, Fewer said.

"If you really want to protect yourself, you really have to do it," he said.

And although the real problem in the B.C. case was the app used by the teenager's girlfriend, knowing how the software works on your phone can help save expensive charges for friends, family and colleagues.

2. Research the app

Another suggestion to help avoid unplanned charges is to do some research before downloading the app, said John Lawford, counsel with the Public Interest Advocacy Centre.

This can involve searching news stories or tech websites to see if a particular type of software has been the subject of complaints, which might be an indication to steer clear.

It's also useful to consider the company that is offering the app, according to Maker from the CCTS. He recommends only downloading software from trusted sources and avoiding small, relatively unknown companies.

3. Check your usage

Another option to avoid hefty fees is to monitor your usage as closely as possible to watch for any unusual activity, said Mel Fruitman, vice-president at the Consumers' Association of Canada.

A number of providers offer almost constantly updated information on how many minutes or gigabytes of data a person has used. Some phones also provide a history of usage over a certain period of time. Sudden changes in this data could signal a potential problem.

However, being reactive is unlikely to completely prevent some unwanted fees, Fruitman said.

"You'll get caught for some but at least you'll try to minimize the damage," he said.

4. Make a complaint

If you do end up getting a massive bill for seemingly unexplained charges, talk to your service provider to see if it is willing to forego some or all of the extra charges, Fewer said.

'You can't give all the responsibility to the consumer.' —John Lawford, Public Interest Advocacy Centre

Maker also recommends filing a complaint with his organization to see if there are any other remedies available to you. The CCTS also issues an annual report detailing key topics and trends in the industry, so reporting problematic apps can bring further scrutiny.

For Lawford, bringing potential issues into the public sphere is the first step in moving towards stronger consumer laws which could prevent the frequency of bill shock.

One possible solution would be to institute a system where cell providers notify customers when there is suspicious activity with their account, including a sudden increase in expensive international text messages or a sudden spike in data usage, he said.

"I just think at a certain level, you can't give all of the responsibility to the consumer," Lawford said.

Although a number of provinces, including Ontario, Quebec and Manitoba, have either passed or are working towards stronger protections in the telecommunications market, widespread changes are a long way off, he said.

"We haven't even gotten close to talking about this," Lawford said. "It's totally buyer beware."