Signalling (telecommunication)
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Signaling In Telecommunications
In telecommunication, signalling (or signaling) has the following meanings:
- The use of signals for controlling communications.
- In a telecommunications network, the information exchange concerning the establishment and control of a connection and the management of the network, in contrast to user information transfer.
- The sending of a signal from the transmitting end of a circuit to inform a user at the receiving end that a message is to be sent.
Telephony
In telephony, signaling is the exchange of information between involved points in the network that sets up, controls, and terminates each telephone call. In in-band signaling, the signaling is on the same channel as the telephone call. In out-of-band signaling, signaling is on separate channels dedicated for the purpose.
In-Band Signaling
In the public switched telephone network, (PSTN), in-band signaling is the exchange of signaling (call control) information on the same channel that the telephone call itself is using. Today, most long-distance communication uses out-of-band signaling as specified in various Signaling System 7 (SS7) standards.
Out-Of-Band Signaling
Out-of-band signaling is telecommunication signaling (exchange of information in order to control a telephone call) that is done on a channel that is dedicated for the purpose and separate from the channels used for the telephone call. Out-of-band signaling is used in Signaling System 7 (SS7), the latest standard for the signaling that controls the world's phone calls.