A prototype of an Apple phone has been uncovered and it dates all the way back to 1983. Designer Hartmut Esslinger came up with the design whilst working for Apple on other projects such as the Apple IIc. Wikipedia has it noted that Esslinger was contracted to Apple in a $1,000,000 a year deal.
In 1982 he entered into an exclusive $1,000,000 per year contract with Apple Computer to create a design strategy which transformed Apple from a "Silicon Valley Start-Up" into a global brand. Setting up shop in California for the first time, Esslinger and Frogdesign created the "Snow White design language" which was applied to all Apple product lines from 1984 to 1990, commencing with the Apple IIc and including the Macintosh computer.
This information is confirmed in the recent Steve Jobs biography too but there was no mention of an Apple phone prototype. Looking at the picture, it is obviously a fixed line phone rather than a mobile device. It is interesting to note that even in the early 1980’s the device still has some form of touch input; even if it was via a stylus!