A car phone is a mobile phone device specifically designed for and fitted into an automobile. This service originated with the Bell System, and was first used in St. Louis on June 17, 1946.
The original equipment weighed 80 pounds (36 kg), and there were initially only 3 channels for all the users in the metropolitan area. Later, more licenses were added, bringing the total to 32 channels across 3 bands (See IMTS frequencies). This service was used at least into the 1980s in large portions of North America. On October 2, 1946, Motorola communications equipment carried the first calls on Illinois Bell Telephone Company's new car radiotelephone service in Chicago. Due to the small number of radio frequencies available, the service quickly reached capacity.
In Finland, car phone service was first available in 1971 on the zero-generation ARP (Autoradiopuhelin, or Car Radiophone) service. This was succeeded in 1982 by the 1G system NMT (Nordic Mobile Telephone), used across Scandinavia and in other often remote areas. In North America, car phone typically used the Mobile Telephone Service (MTS), which was first used in St. Louis, or Improved Mobile Telephone Service (IMTS) before giving way to analog cellular service (AMPS) in 1984. AMPS technology was discontinued in the United States in 2008.
Since a traditional car phone uses a high-power transmitter and external antenna, it is ideal for rural or undeveloped areas where mobile handsets may not work well or at all. However, due to current US Federal Communications Commission regulations, carriers must pay penalties for activating any equipment that is not an E911 compliant device, such as analog.