Telecom Basics, Second Edition
This guide presents the groundwork of telecom technolgies, network, systems, and call processing.
TABLE OF CONTENTS Telecom Basics, Second Edition
Chapter 6: Signaling
Signaling is the process of transferring control information such as connection addresses, call supervision codes, or other connection information between communication switching equipment and other communications equipment or systems. The basic functions of signaling include initiate a call or line connection (call setup), maintain a communication link, and to end a call or connection (call teardown). Signaling comes in two basic forms: in-band signaling and out-of-band signaling.
The control of public telecommunications networks is a centralized system as call processing is coordinated through a controlled common channel signaling (CCS) network. The Internet uses distributed control as the switching information dynamically changes in packet switching centers (routers) throughout the Internet network.
In-Band Signaling
In-band signaling sends control messages in the same communication channel that is used for voice or data communication. During the period of in-band signaling, the voice or data communication is temporarily inhibited (muted) to allow the transfer of control messages. The types of in-band address signaling include dial pulse (DP), dual-tone multi-frequency (DTMF), MF (Multi-Frequency), audio signaling, and line control. In-band signaling is sometimes called blank and burst signaling.
Dial pulse (DP) signaling senses and counts the changes in current flow, such as from a rotary dial telephone, to allow the user to send address information (dialed digits) to the telephone system.
DTMF signaling is a means of transferring information from a user to the telephone network through the use of in-band audio tones. Each digit of information is assigned a simultaneous combination of one of a lower...
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