The billboards feature images of key fashion items that consumers can purchase by scanning the item's barcode with their iPhone. The QR (quick response) code takes the shopper directly to the Sportsgirl mobile store, where they can buy the item with a click of a button and have it delivered to their home.

''I've always got my iPhone in my hand. So this is perfect for me,'' said Ms Tran, a lifestyle and fashion blogger, who does most of her shopping online. ''I would definitely use something like this.''

Sportsgirl strategic brand manager Prue Thomas said the billboards were designed specifically for consumers like Ms Tran who always have their mobile within reach and are increasingly shopping on the run.

Paypal says it now processes more than 1000 transactions per hour from mobile phones.

''When we looked at the way our consumers were interacting with us, mobile phones and then iPads surpassed everything else. They like to shop on the go,'' Ms Thomas said. ''So this is really about trying to get online to meet offline in a completely symbiotic way.''

Virtual billboards first sprang up overseas last year when British grocery retailer Tesco installed virtual grocery stores on the walls of Korean train stations so commuters could order their groceries using their smartphones on their way home from work.

Similar billboards are now being installed in American subways by US online grocery retailer Peapod.

Meanwhile, online fashion retailer Netaporter.com also installed an interactive window shop in London last year.

Chris Sanderson, co-founder of trend forecasting group The Future Laboratory, which held a seminar in Melbourne yesterday, said blurring the line between online shopping and bricks and mortar stores was the way of the future.

''Retailers need to understand that online shopping isn't something we just do at our desktops any more. We now do it out in the real world, out on the streets and often while we're in-store. That's where the real growth is.''

Read more: http://www.theage.com.au/technology/technology-news/virtual-shop-perfect-for-the-young-and-upwardly-mobile-20120215-1t6qa.html#ixzz1n4L0mz6c