Conspiracy theorists have become excited following the posting of a video claiming to show an 800-year-old mobile phone with a keypad with cuneiform characters that were used in ancient Mesopotamia 3,000 years ago. The Paranormal Crucible channel claimed the "discovery" was made during an archaeological dig in the Austrian city of Salzburg earlier this year (2015).

To most untrained eyes, the images in the video appear to show a crudely-made mock phone on which old symbols have been inscribed. However to conspiracy theorists, the video is evidence of something more unusual - they just aren't sure whether it shows aliens landed on earth, time travel has occurred - or both.

"It is evident from this cell phone-like device that someone with an advanced knowledge of the future created it," wrote UFO expert Scott Waring. "The language is said to go back tens of thousands of years...very cool discovery."

Antikythera Mechanism
The Antikythera MechanismGiovanni Dall'Orto/Creative Commons

However sceptics point out that so far little information has emerged about the so-called phone, which resembles a Nokia made out of something more durable. Nor has anyone explained why the device apparently has no reception - or the huge amounts of voicemail messages that would surely have built up over 800 years.

"Searching the internet didn't help much as the information about the artefact is extremely limited," said conspiracy website tothedeathmedia.com. "The only thing we managed to find out is that it was allegedly discovered in...modern-day Austria."

However the Paranormal Crucible channel, which posted the video to YouTube, says it has evidence of other artefacts "proving" time travel exists, and has posted images of what appear to be ancient depictions of laptops. Other examples of so-called "out-of-place artefacts" include Helicopter hieroglyphs and the Antikythera mechanism which some experts believe is a primitive computer dating from 100-200 BC.