Unlimited free SMS and possibly free mobile phone calls in the future. That's the offering by newly launched Australian mobile service provider, mobiK.

"Your mobile phone should be free. You shouldn't have to pay", said Damian Thompson, CEO of mobiK.

But for now users will have to as mobiK will only be offering free SMS. Thompson said he could see a time in the future when it would provide free voice calls, but didn't say when.

mobiK began its free mobile services in October last year. The company claims to have 400,000 users today, mainly in Asia. Worldwide it has negotiated coverage deals with 397 carriers including all of Australia's leading mobile providers.

Until this week subscribers have been able to send free Internet to mobile, and mobile to Internet texts. Now they are also be able to send free mobile to mobile messages.

mobiK is an ad serving business. Thompson said it relies solely on advertisers to run as it ask for no money whatsoever from subscribers. In return for their investment advertisers get a banner ad on the mobiK site, a 5-7 second video of their product, also on the site, and text tag at the bottom of each SMS that is no more than 40 characters long.

To use the service customers need to sign up. During this registration process they offer basic information about themselves and their age, with a minimum age of 13 required.

Thompson said the information is enough to pass on to advertisers to provide targeted ads.

"If I am a 13 year old girl they [advertisers] wont show me an ad for a $5000 phone," he said. "We are not squeezing an ad in every page. It is about user experience."

He said the target audience would be the teen to 30 year old demographic.

Thompson also said the registration process would prevent spam.

"The last thing we want to do is become a tool for spammers. By forcing someone to be a member we need your details so should something untoward happen later on we can put your details to law enforcement officials."

Mobile phone users over 13 are the target audience.

Along with free SMS, users that sign up also partake in the rewards program called K. People earn rewards by filling out surveys for sponsors or by signing up their friends. Once they build up enough K they can redeem them for ring tones, phones or retail vouchers in chain stores such as Starbucks.

Providing free SMS is not new. During the dot com boom many service providers came and then went. Some such as BluSkyFrog remain.