ADTRAN 1200070L1, 1200070L2 user manual Isdn Connection

Chapter 1: Understanding ISDN and the Express XL/XLT

ISDN Connection

From the network, ISDN is delivered by a single 2-wire 2B1Q U-interface which is connected directly to the Express XL/XLT. ISDN network termina- tion is designed into the Express XL/XLT, eliminating the need and expense of a separate NT1. For network testing, the Express XL/XLT responds to NT1 test commands from the telephone company central office (CO).

The Express XL/XLT has one RJ-45 jack, labeled ISDN BRI U on the rear panel for network connection (see Figure 1-7). ISDN basic rate service divides a stan- dard telephone line into three digital channels capable of simultaneous voice and data transmission. The three channels are comprised of two bearer (B) channels at 64 kbps and one data (D) channel at 16 kbps, known as 2B+D.

The Express XL/XLT also supports a leased digital connection allowing data to be transferred at up to 144 kbps over a 2-wire facility using the same RJ-45 jack. This type of service is a permanent connection between endpoints and is sometimes referred to as a leased connection, a dedicated connection, a nailed- up connection, or a private circuit. Leased connection or leased line is used in this manual to represent these types of services.

ISDN		TO TO	10BT
BRI U	MAINTENANCE			POWER
		NIC HUB

1200070L1

ISDN	PHONE		TO TO	10BT
BRI U		MAINTENANCE			POWER
			NIC HUB

1200070L2

Figure 1-7

Express XL/XLT Rear Panels

18 Express XL/XLT User Manual 61200.070L1-1