Modular Portable Cellular Device Layout and Connection System

An expandable cellular phone includes system for allowing the cellular phone to physically mate with, and electronically link to, an independently functional auxiliary module. The system includes a contact face on a backside of the device to mate to a corresponding back face of the auxiliary module. The back face of the expandable cellular phone includes at least one electrical contact at a location mirroring a location of a mating electrical contact on the corresponding face of the auxiliary module. Moreover, at least two locating points are provided on the back sides if both devices, with each locating point on one device including a locating pin, and each corresponding locating point on the other device including a receptacle for the locating pin.