The first cell phone was invented by Dr. Martin Cooper, who was working for Motorola when he developed the first working prototype called the Dyna-Tac by Motorola.
"On April 3, 1973, standing on a street near the Manhattan Hilton, Mr. Cooper decided to attempt a private call before going to a press conference upstairs in the hotel. He picked up the 2-pound Motorola handset called the Dyna-Tac and pushed the "off hook" button."
Both Motorola and AT&T were attempting to create the network of antennas that would support cell phone service.
"While AT&T developed a system based on mobile (car) phones, Motorola decided to apply its decades of radio expertise and compete with AT&T for access to the proposed new radio frequencies."