From its start in St. Louis in 1946, AT&T introduced Mobile Telephone Service to one hundred towns and highways by 1948. Mobile Telephone Service was a rarity with only 5,000 customers placing about 30,000 calls each week. Calls were set up manually by an operator and the equipment weighed about 80 pounds.
Subscriber growth was hampered by the limitations of the technology. Because only three radio channels were available, only three customers could make mobile telephone calls at one time. Mobile Telephone Service was expensive, costing equivalent to about $176 per month and $3.50 to $4.75 per call in 2012 dollars.
AT&T introduced the first major improvement to mobile telephony in 1965, creating the Improved Mobile Telephone Service. IMTS allowed more simultaneous calls in a given geographic area, introduced customer dialing, and reduced the size and weight of the equipment.
European mobile radio networks
In Europe, several mutually incompatible mobile radio services were developed. West Germany had a network called A-Netz launched in 1952 as the country’s first public mobile phone network. In 1972 this was displaced by B-Netz which connected calls automatically.
Philip T. Porter of Bell Labs first proposed that the cell towers use the directional antennas to reduce interference and increase channel reuse.
Handheld mobile phone
Prior to 1973, mobile telephony was limited to phones installed in cars and other vehicles. Motorola was the first company to produce a handheld mobile phone on 3 April 1973, when Martin Cooper, a Motorola researcher and executive, made the first mobile telephone call from handheld subscriber equipment, placing a call to Dr. Joel S. Engel, from Bell Labs. The prototype handheld phone used by Dr. Cooper weighed 2.5 pounds and measured 9 inches long, 5 inches deep and 1.75 inches wide. It offered a talk time of just 30 minutes and took 10 hours to re-charge.
John F.Mitchell, Motorola’s chief of portable communication products and Martin Cooper’s boss in 1973, played a key role in advancing the development of handheld mobile telephone equipment. Mitchell successfully pushed Motorola to develop wireless communication products that would be small enough to use anywhere and participated in the design of the cellular phone.