Telcos and internet service providers often update their plans throughout the year but existing customers, particularly those who are less tech-savvy or time poor, may not realise they could be paying less or getting much more for the same price.

And telcos may not exactly be beating down their customers' doors to tell them.

''Telcos and internet service providers rely on the fact that most of us think it's too hard to change to another provider, so once they have got your business, they stop competing for it,'' Alan Kirkland, the chief executive of the consumer group Choice, said.

''This means that you can often be paying much more on your monthly bill than what your telco is offering to newer customers.''

Mr Kirkland said consumers could save hundreds of dollars a year simply by ringing their provider and asking to switch plans.

Alister Robbie had been regularly going over his 60GB data allowance, often paying Internode $30 extra on top of his monthly $69.95 broadband plan to buy additional data blocks.

Last year the Melbourne film editor checked Internode's website and found he could for some time have been getting 150GB for the same price.

''It's annoying when you find out you could be saving all this money each month and because I'm interacting with the company each month to buy the data blocks - you'd think it'd come up on their radar,'' Mr Robbie, 35, said.

Robin Hutcheon, 84, of Edgecliff, has been on the same iPrimus plan since 2008, paying up to $105 a month for his phone and internet package with a 2GB data allowance. When he called iPrimus two weeks ago he found he could be paying half the price for a new plan with over twice the included value.

''It's the first I'd heard about that new deal. I would've been on to it earlier if I had known,'' Mr Hutcheon said.

Elise Davidson, a spokeswoman with the Australian Communications Consumer Action Network, said customers sometimes see great deals being offered by their existing provider but when they ask about it are told it is only for new customers.

''Providers are under no obligation to tell you about cheaper or better value plans, although the good ones will,'' Ms Davidson said.

''You should be rewarded for your loyalty, but often it's customers who have been with the same provider for a long time who are getting the worst deal.''

The networks' National Consumer Perceptions Survey, published in September, revealed that many people were reluctant to switch providers, with almost a third saying they had never switched telecommunications providers and almost half having stayed with their provider for five years or more.

The survey found respondents aged 55 and over were significantly more likely to have never changed providers.

Telstra, Optus, iiNet and Vodafone said customers could call at any time to discuss their plans and while they generally attempted to inform customers about new deals, Vodafone said it did not contact every customer about new plans.