Australia-based mobile operator Optus is seeking compensation from Telstra after a federal court ruled an advertising campaign by the market leader for unlimited data plans could mislead consumers, ZDnet.com reported.

Optus today (1 June) asked the Federal Court of Australia for data from Telstra to determine how many customers it potentially lost from its rival’s campaign.

Telstra’s ad stated: “One word from Australia’s best mobile network: Unlimited.”

Optus argued in court consumers could assume the ad referred to unlimited network coverage and unthrottled data speeds, while Telstra contended the industry is “awash” with unlimited advertising, ZDnet.com said.

Last week the court issued an injunction requiring Telstra to stop its unlimited campaign after finding it was misleading and deceptive.

Justice J Gleeson said in a ruling the ads “falsely convey the representation that Telstra offers a mobile product that is unlimited in the sense that it imposes no limits on data speeds, data volumes and the user’s ability to download data without interruption or delay…The respondent has engaged in conduct that is misleading or deceptive”.

In early May Telstra and Vodafone Australia unveiled unlimited mobile data plans which they said were designed to end excess data charges and free subscribers from worrying about additional charges.