The competition watchdog is examining public comments by Telstra, SingTel-Optus and Vodafone Hutchison Australia executives to see whether they represent price signalling in relation to the rising cost of popular smartphones.

Price signalling involves companies releasing information to reduce competition in the market. Australia's big four banks were often accused of doing it because they told the market about plans to pass on interest rates until fresh laws were passed in 2012 to stop the practice.

Smaller subsidies from the telcos on smartphones has raised costs for consumers.

Telstra, SingTel-Optus and Vodafone Hutchison Australia have all cut the subsidies they pay on popular smartphones such as Apple's iPhone 5 over the past two years. This has come with comments by senior executives at all three companies flagging the trend.

The result has been higher prices for consumers and rising profits for the telcos because the cost of smartphones is a massive burden on the industry. Most popular smartphones in Australia are bought through telcos as part of a plan.