It was bound to happen, sooner than later actually, but Vodafone's stock of pay-as-you-go Apple iPhone 4 units have been depleted – meaning that they're currently sold out for the moment. In less than a day, customers jumped on the opportunity like a pack of hungry wolves to scope a prized handset online. Taking a quick gander over their web site, they provide that slight hint of optimism by stating that “more are on the way”, but there is no definite time indication for when replenishment is expected to arrive. In the mean time, you can still place an order for the pay-as-you-go iPhone 4, but expect to wait some time before actually receiving one since the wait is based on a first come, first served basis. There's no denying that demand for the smartphone is still high – even when we're nearing the two month mark since the handset launched.