Cellular Circuit-Switched Data (CCSD)

Transmitting data over a circuit-switched call is similar to transmitting data over a landline phone except transmission also occurs over the cellular network. When making a cellular data call, a modem is required to talk to another modem. The laptop computer is connected to a modem which is then connected to a cellular phone instead of through an RJ11 landline telephone jack. Once the modem-to-modem connection is established, the channel is dedicated to the session until one terminates the session. From the perspective of the cellular phone system, the circuit-switched data call is processed as a regular cellular voice call. There are no operational differences between how the voice and data calls are handled. All the principles and procedures of the AMPS cellular network, such as roaming, hand-offs and routing of calls through the cellular provider's central office, apply.

Coverage

Since cellular circuit-switched data communications use the AMPS network, coverage is available anywhere there is cellular service. Approximately 95% of the U.S. population has cellular coverage, and AMPS service is available in over 30 countries.

Equipment

Because of the dynamic nature of a cellular environment, problems that go unnoticed using voice communications can have a damaging effect on data communications. Man-made and natural structures such as buildings, tunnels, trees, hills and valleys can block or cause interference with the signal. Channel interference that degrades the quality of a voice call may also make a data connection more difficult. To maximize the effectiveness of circuit-switched data calls, special consideration must be given to the hardware technologies.