In North American digital cellular radio systems based on IS-136 and generally known as Digital Advanced Mobile Phone System (D-AMPS), a channel that supports residential and in-building coverage, increased battery standby time, text messaging via short message service (SMS), over-the-air activation, circuit-switched data (CSD), and caller ID. See also cellular radio, channel, CSD, D-AMPS, digital, IS-136, SMS, and text messaging.