The Australian Competition and Consumer Commission (ACCC) has filed proceedings against Singtel Optus in Federal Court over the telco's claims of offering "unlimited" mobile, broadband and landline products.
The allegations relate to advertisements Optus has recently aired on television, radio and print.
The regulator said in a statement that the telco's claims were misleading and deceptive "because the offer is subject to a number of limitations and restrictions".
Specifically, the ACCC has viewed Optus' "$70 pre-paid Turbo Max plan" as deceptive and misleading.
While the regulator did not identify what restrictions led to its allegations, Optus' web page states that its Turbo Max $70 recharge gives "Unlimited calls to any mobile numbers up to a maximum of 3000mins per recharge plus $70 Credit."
Its offer also excludes satellite, premium and international calls, while the deal is not to be used for "commercial purposes".
Optus isn't the first to face such allegations. Last February, the ACCC took internet service provider TPG to task over advertising "unlimited" plans, which in fact excluded calls to 1800, 13, 1300 numbers and text SMS.
The ACCC said it would seek declarations that Optus had contravened Section 52 of the Trade Practices Act in making its "unlimited" claims and will apply for costs.
The pair will square off on 25 June 2010 in the Federal Court, Melbourne.