Telstra may be forced to let competitors in on its mobile network in regional and remote areas.

The Australian Competition and Consumer Commission (ACCC) has launched an inquiry and discussion paper calling on industry and consumer views on whether Telstra should “declare” domestic mobile roaming services.

It could see Telstra ordered to let its competitors use its mobile network in areas where they otherwise would not have coverage.

People in rural and remote areas often have only one choice when it comes to mobile service, as Telstra is the only company to have built networks in many regions.

Telstra has spent billions on its mobile network, which it plugs as a key difference between it and other telcos like Optus and Vodafone.

“Declaring mobile roaming would stop coverage being a differentiator in the Australian market and therefore, remove the key rationale for investment in regional Australia for all operators,” Telstra group executive corporate affairs, Tony Warren, said in a statement to the stock market.

“Where there is lack of choice of operators for regional Australians, it is the result of decisions by our competitors to not invest in those areas. Declaration would ensure there is no incentive for any operator to invest for competitive reasons in many regional areas.

“We have only just been made aware of this inquiry so we must now consider the implications of potential roaming regulation for our investment plans.

“We look forward to the conclusion of this inquiry as quickly as possible so the industry can get on with providing better mobile coverage and service for regional and rural Australians.”

ACCC chairman Rod Sims said the inquiry would look at what is stopping other telcos from expanding into regional areas.

“We are getting a lot of pressure from regional interests who argue that they only have one choice of mobile supplier, and that's Telstra because they are the only one with infrastructure out there in regional areas,” Mr Sims told Fairfax.

“Telstra's competitors have been pushing the point as well.”

Telstra has not done all the hard work itself though, with recent reports from the Australian National Audit Office showing that much of a $220 million government program to fix mobile black spots in regional areas went to Telstra.

The auditors found that out of 499 base stations upgraded with public money, 427 belong to Telstra.

Vodafone released a statement backing calls to declare mobile services.

“Australia has less infrastructure-sharing and roaming than is seen in most global markets, leading to a telecommunications divide which is disadvantaging many Australians,” Vodafone chief strategy officer Dan Lloyd said.

A draft decision is expected by February.