IS-136 Overview

IS-136, A.K.A. IS-54C, is the 2nd generation North American digital cellular standard. IS-136 is essentially the same as IS-54B but adds additional features such as a digital control channel, SMS service, multiple data services, a sleep mode timer, over-the-air activation, the capability for micro-cell applications, increased network capacity, voice encryption, and caller ID.

IS-136 is a Time Division Multiple Access (TDMA) cellular standard.

The specs are as follows:

Same transmission specs as IS-54B. See IS-54B report for further details.
IS-136 can operate in either IS-136, IS-54B, or AMPS mode. Operates in the same spectrum allocated for AMPS/IS-54B and is 100% compatible.
Based on the OSI (Open System International) reference model for standardizing communication protocols.
Short message services (SMS) - Paging service in which short (239 byte) messages can be sent to individual users or broadcast to the entire network.
Sleep mode timer - capable of shutting power off during non-critical times, thus extra-long battery life.
Digital Control Channel -Instead of using dedicated control channels as in AMPS/IS-54B systems, individual time slots are used. This increases user capacity since entire channels are not being tied up for control purposes as in the AMPS/IS-54B systems.
Micro-cells can be established for residential, campus-wide, and other systems with existing TDMA cellular- service areas.