Dialogic 6.2 manual Loop Start Signaling, November 302

Loop Start Signaling

Loop Start Signaling

Brooktrout modules support two types of loop start signaling:

„FXO Loop Start

„FXS Loop Start

When operating in FXO mode, the module assumes the far end of the connection is an FXS termination. When operating in FXS mode, the module assumes the far end is an FXO termination.

FXS Loop Start is the protocol used for Brooktrout's analog modules. The sequence of events and timings is the same for both analog or digital line interfaces.

The timing diagrams in this section show the Receive and Transmit Signaling Bits in reference to the digital signaling mode. The analog signals are a direct mapping of the signaling bits.

In the FXS diagrams, the electric signals sent by the station are represented in bit A: loop current presence (off-hook) is represented by setting bit A high (one); absence (on-hook) by bit A low (zero). Bit B does not change. The signals received by the station, ring signal and loop current feed (battery), are represented using both A and B bits: loop current feed is represented by setting bit A low (zero); absence by bit A high (one). Presence of ring signal is represented by setting bit B low (zero); absence by bit B high (one).

The FXO diagrams are the mirror-image of the FXS diagrams. The signals sent by the module (FXO) toward the network (FXS) are the same that the station (FXS) received from the network (FXO) on the FXS diagrams.

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