What about Gene Rodenberry and the personal communicator carried by Captain Kirk and all the landing parties in the original 1960's series of Star Trek.
I would say that little hand held device which allowed the Captain to talk to the Enterprise, gave the transporter crew all the co-ordinates for pick-up might pretty well equate with the cell (mobile) phone of today. After all we now have phones with GPS, e-mail, computer links to the internet and we can talk to anyone who is willing to answer their little communications device.
Bleep, bleepty, bleep. :)