IS-136 is a second-generation cellular technology used in North America. It is also known as Digital AMPS (D-AMPS) and is an extension of the analog Advanced Mobile Phone System (AMPS). IS-136 uses a combination of Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) to support multiple users on the same radio channel.

Voice Channels in IS-136

Each 30 KHz radio channel in IS-136 can support three voice channels. TDMA is used to divide each radio channel into three time slots, each of which can carry a separate voice channel. Therefore, a single radio channel can support three concurrent calls.

Other Features of IS-136

Apart from supporting voice channels, IS-136 has other features that make it a popular cellular technology. Some of these features are:

1. Call Waiting: IS-136 supports call waiting, which means that if a user is already on a call and another call comes in, the user can put the first call on hold and answer the second call.

2. Call Forwarding: IS-136 allows users to forward their calls to another number in case they are unavailable to take calls.

3. Caller ID: IS-136 displays the number of the incoming call so that the receiver can identify the caller.

Conclusion

IS-136 is a popular cellular technology used in North America. Each 30 KHz radio channel in IS-136 can support three voice channels using TDMA. In addition to voice channels, IS-136 has other features such as call waiting, call forwarding, and caller ID that make it a versatile technology.