TUCoPS :: Phreaking Technical System Info :: trunksig.htm

Basics of Telephony Trunk Signaling
Trunk Signaling

Trunk Signaling Schemes

It is necessary to understand the signaling that occurs on trunk circuits. Signaling states include ON-HOOK and OFF-HOOK supervision, Disconnect supervision, dialing supervision (Pulse Dial/Tone Dial), and Start Dial supervision.

Most signaling schemes use DC currents to represent signaling states, but analog (AC) systems also exist that use tones to represent specific states.

The following subsections discuss the types of signaling:

2-Wire Loop Start Trunk Signaling
2-Wire Ground Start Trunk Signaling
SF Signaling (AC Signaling)
E and M Signaling
Start Dial Supervision

Other text on Signaling

Analogue Signalling Systems By  NeonDreamer
Branches Of Signalling         By  dialect
Telephone Signalling Methods       By  Doom Prophet
Signalling Systems         By  Unknown

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