Rumors of an Amazon smartphone are once again making the rounds a little over a week after the company launched its first set-top box. The online retailer's goal is to have the phone ready for production by June and ship it this September according to people briefed on the matter as reported by The Wall Street Journal.

Sources told the publication Amazon demonstrated prototypes of the device to developers in Seattle and San Francisco over the past few weeks.

To differentiate it from other devices already on the market, Amazon's smartphone will feature a screen capable of displaying 3D images without the need for silly glasses. It would use four front-facing cameras to track the position of a user's head and arrange the on-screen effects accordingly. The effect would be similar to a hologram, the sources said.

If ever there was a persistent rumor that has yet to materialize, the Amazon smartphone ranks right up there with the Apple television set and the iWatch. Rumblings of such a device date back to late 2011 when supply chain checks suggested Amazon would be working with Foxconn to manufacture it. Around this time last year, we caught wind of the 3D display so even that revelation isn't new to the rumor mill.

It's the rumor that never dies, even when Amazon publically denies it. Perhaps the consensus is that if you keep talking about something long enough, it'll eventually become a reality.