With the Air-Ground Radiotelephone Service, a commercial mobile radio service (CMRS) provider offers two-way voice, fax, and data service for hire to subscribers in aircraft—in flight or on the ground. Service providers must apply for an FCC license for each and every tower/base site. There are two versions of this service: one for general aviation and one for commercial aviation.
General Aviation Air-Ground Service
Air-Ground Radiotelephone Service has been available to general aviation for more than 30 years. General Aviation Air-Ground systems may operate in the 454.675- to 454.975- MHz and 459.675- to 459.975-MHz bands to provide service to private aircraft, specifically, small single-engine craft and corporate jets.
The service is implemented through general aviation air-ground stations, which comprise a network of independently licensed stations. These stations employ a standardized duplex analog technology called “Air-Ground Radiotelephone Automated Service” (AGRAS) to provide telephone service to subscribers flying over the United States or Canada. Because there are only 12 channels available for this service, it is not available to passengers on commercial airline flights.
Commercial Aviation Air-Ground Systems
Commercial Aviation Air-Ground Systems may operate on 10 channel blocks in the 849- to 851-MHz and 894- to 896- MHz bands. These nationwide systems employ various analog or digital wireless technologies to provide telephone service to passengers flying in commercial aircraft over the United States, Canada, and Mexico.
Some systems have satellite-calling capability as well, where the call is sent to an earth station instead of the base station. Passengers use credit cards or prearranged accounts to make telephone calls from bulkhead-mounted telephones or, in larger jets, from seatback-mounted telephones. This service was available from one company on an experimental basis during the 1980s and began regular competitive operations in the early 1990s. There are currently three operating systems, one of which is GTE Airfone, a subsidiary of Verizon Communications.
When an Airfone call is placed over North America, information is sent from the phone handset to a receiver in the plane’s belly and then down to one of the 135 strategically placed ground radio base stations. From there, it is sent to one of three main ground switching stations and then over to the public telephone network to the receiving party’s location.
When an Airfone call is placed over water, information is sent first to an orbiting satellite. From there, the call transmission path is similar to the North American system, except that calls are sent to a satellite earth station instead of a radio base station. Calls can be placed to any domestic or international location.
To receive calls aboard aircraft, the passenger must have an activation number. In the case of Airfone, an activation number can be obtained by dialing 0 toll-free onboard or 1-800-AIRFONE from the ground. For each flight segment, the activation number will be the same. However, the passenger must activate the phone for each flight segment and include his or her seat number.
The person placing the call from the ground dials 1-800-AIRFONE and follows the voice prompts to enter the passenger’s activation number. The passenger is billed for the call on a calling card or credit card but gets to choose whether or not to accept the calls. The following steps are involved in receiving a call:
- The phone will ring on the plane, and the screen will indicate a call for the seat location.
- The passenger enters a personal identification number (PIN) to ensure that no one else can answer the call.
- The phone number of the calling party will be displayed on the screen.
- If the call is accepted, the passenger is prompted to slide a calling card or credit card to pay for the call.
- Once the call has been accepted, the passenger is automatically connected to the party on the ground.
- If the passenger chooses not to accept the call, he or she follows the screen prompts, and no billing will occur.
Air-to-ground calls are very expensive. The cost to place domestic calls using GTE’s Airfone Service, for example, is $2.99 to connect and $3.28 per minute or partial minute, plus applicable tax. By comparison, AT&T’s Inflight Calling costs $2.99 to connect plus $2.99 per minute. These rates apply to all data/fax and voice calls. Even calls to 800 and 888 numbers—which are normally tollfree on the ground—are charged at the same rate as regular Airfone and Inflight calls.
No billing ever occurs for the ground party. The charges for international calls are higher; both AT&T and GTE charge $5.00 to connect and $5.00 per minute. GTE offers satellite service for use over the ocean and worldwide at $10.00 to connect and $10.00 per minute, but the service is available only on United Airlines.
FCC rules specifically prohibit the use of cellular transmitters on aircraft, except for aircraft on the ground. This prohibition was not done to protect the aircraft’s avionics systems from interference from the cellular transmitter. Rather, this prohibition was made to protect the cellular service on the ground from interference.
As the altitude of a cellular handheld transmitter increases, its range also increases and, consequently, its coverage area. At high altitudes, such as would be achieved from an in-flight aircraft, the hand-held unit places its signal over several cellular base stations, preventing other cellular users within range of those base stations from using the same frequency. This would increase the number of blocked or dropped cellular calls.