[RedMonqey]

Why would a time traveler, whose not of our current time period, stop here in our present, pick up a cellphone, then travel to another time period where this same item is useless.
The gut is scratching the side of his head.

[stig]

Why would a time traveler, whose not of our current time period, stop here in our present, pick up a cellphone, then travel to another time period where this same item is useless.

It's not a cell phone it's a quantum entanglement communication device invented in the early 23rd century a few years after human time travel was made possible. But if I say any more I risk changing this timeline.