partnered with Southwestern Bell (SBC©
) under the trade name Cingular©,
was a U. S. provider of Mobitex©
network services until Fall 2004
when Cingular Interactive©
was sold to a venture capital corporation. Six months before the sale of
purchased AT&T Wireless©
becoming the largest domestic cell service in North America.
Like mobile telephone systems, the Mobitex© network is based on radio cells, with radio links replacing the wiring that connect telephones or data terminals to networks. Intelligent base stations provide the links by allocating channels to active terminals within limited geographic areas. The size of a radio cell is determined by such factors as the number of channels available, the maximum number of units served and the output power of both the terminals and the base station.
Base stations serve several essential functions in the Mobitex© system. First and foremost, they function as connection points so that calls or messages can be switched from one base station or local exchange in the telecommunications network to another.
A second function of base stations is the ability— in conjunction with mobile user devices — to hand off calls as users change locations. This is the function that makes roaming possible. This concept is similar to circuit-switched cellular networks as described earlier.
Acting as network nodes is a third function of base stations. Base stations forward statistics to the network for subscriber billing and distribution of traffic loads across the network