The ACMA said the two companies have allegedly engaged in 'missed call' marketing and that these marketing activities are likely to constitute serious and extensive contraventions of the Spam Act 2003.

Following ACMA's intervention, the companies responsible have now stopped making these calls while the ACMA continues investigating.

'Missed call' marketing is the term that has been given to the practice of calling a mobile telephone for such a short period of time that the owner cannot answer the call.

When the marketer disconnects the call, most mobile phones present a 'missed call' notification with the marketer's number. The marketer intends that the owner of the phone will think they have missed a legitimate call and phone the number back, at which time they hear a recorded promotional message.

ACMA industry output division general manager Nerida O'Loughlin said it is similar to receiving e-mail spam which includes nothing except a link to a Web site.