I presume you are also Alesha?
As an item the mobile phone can be considered a logical extension of walkie talkies which date back to the 1950s. They wre first a walkie talkie that was connected via the operator. What you might want to consider are what are the problems making a unit so small and having so many working at the same time? Is there anything special 'thinking out side of the box' that was needed.
Have a look at some older versions of mobile phones
any obvious problems with these that modern phones do not have?