AT&T DS1/DMi/ISDN-PRI manual Trunks and Trunk Groups, Sample Installation and Maintenance Problems

SAMPLE INSTALLATION AND MAINTENANCE PROBLEMS B-3

	OPTIONS:	CHANGED	OPTIONS:
	D4 FRAMING			D4 FRAMING
●		FROM	●
●	PER-CHANNEL SIGNALING	FIGURE B-1	●	PER-CHANNEL SIGNALING
●	ROBBED-BIT SIGNALING		●	ROBBED-BIT SIGNALING
●	ZCS		●	ZCS

DS1 OR DMI

INTERFACE

TRANSMISSION FACILITY

(2-WAY COMMUNICATION)

DS1 OR DMI

INTERFACE

CALL PROCESSING CAN NOW OCCUR ASSUMING CORRECT TRUNK GROUP

TRANSLATIONS AND PROPER ASSIGNMENT IN PROCEDURE 116.

Figure B-2.Correct Translations (Procedure 260)

TRUNKS AND TRUNK GROUPS

Mistakes in translating procedure 116 are not readily evident. The first indication that a problem exists may not occur until the customer complains of call completion failures.

Table 7-1,DS1 Administration — Channel Versus Line Assignments, and table 7-2,Trunks Supporting Signaling Type 20, list the DS1 channel number assignments versus slot and circuits for System 85. Each end of a DS1 facility must match the assignment of trunks (or off-premises station (OPS) lines) at the other end. For example, if channels 1 through 12 are to be trunk type 75 and channels 13 through 24 are to be trunk type 36, then the assignments must be the same at each end. If location A implements the type 75 trunk starting at slot/circuit location 0/0 and location B incorrectly implements the type 75 trunk starting at slot/circuit location 5/0, then a DS1 facility will come up and appear to operate. However, because of the translations mismatch and trunk signaling incompatibilities, the facility will never support a call between the two locations.

Figure B-3,Incorrect Assignment of Trunks, shows this type of scenario showing an incorrect match of translations. Figure B-4,Correct Assignment of Trunks, shows a correct translations match.