AT&T AT&T manual Signaling Type Summary, Signaling Transmit Receive Type ON-HOOK OFF-HOOK

TABLE 3-B. Signaling Type Summary

SIGNALING	TRANSMIT			RECEIVE
TYPE	ON-HOOK	OFF-HOOK	ON-HOOK		OFF-HOOK
I Std.	grd	bat	open/bat	(*)	grd
I Compat.	open/bat (*)	grd	grd		open/bat (*)
V	open	grd	open		grd

* An open circuit is preferred over voltage.

TABLE 3-C. TN760B Tie Trunk Preferred Signaling Formats

I N S T A L L A T I O N		S I T U A T I O N			PREFERRED SIGNALING FORMAT
					SYSTEM	25		FAR	END
	C I R C U M -			S I M P L E X		PROTECTED	S I M P L E X			PROTECTED
FROM			T O
	S T A N C E S			O R	S I G N A L	O R	O R	S I G N A L		O R
				E & M	T Y P E	U N P R O T E C T E D	E&M	T Y P E		UNPROTECTED
S25	Co-		S25/S75	Simplex	Type V	(Either)	Simplex	Type V		(Either)
	Located
S25	Inter-		S25/S75	Simplex	Type V	(Either)	Simplex	Type V		(Either)
	Building
S25	Co-		S85	Simplex	Type V	(Either)	Simplex	Type V		(Either)
	Located
S25	Inter-		S85	Simplex	Type V	(Either)	Simplex	Type V		(Either)
	Building
S25	Co-		Dim.	E&M	Type I	Unprotected	E&M	Type I		Unprotected
	Building				Compatible			Standard
S25	Inter-		Dim.	E&M	Type I	Protected	E&M	Type I		Protected
	Building				Compatible			Standard
S25	Co-		Other	E&M	Type I	Unprotected	E&M	Type I		Unprotected
	Located				Compatible			Standard
S25	Inter-		Other	E&M	Type I	Protected	E&M	Type I		*
	Building				Compatible			Standard
S25	Co-		Network	E&M	Type I	Unprotected	(Don't	(Don't		(Don’t
	Located		Interface		Standard		Care)	Care)		Care)

* Requires a protection unit.

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