Virgin Mobile USA, a cell-phone service used mostly by teenagers and 20-somethings, said on Tuesday it was giving its customers the option to earn free calls if they view and respond to ads on their phones.

Under the offer, customers of Virgin, a venture of Sprint Nextel and Richard Branson’s Virgin can get up to 75 minutes of free calls per month if they spend an equal amount of time looking at ads and replying to these ads via text messages.

Source: Reuters