Northern UTA220/UTA220k manual ISDN Service, Isdn Switches, 1. ISDN Devices and Reference Points

ISDN

ISDN Service

Figure 4-1. ISDN Devices and Reference Points

To use the ISDN, you must subscribe to a network service. The available options depend on the carrier (telephone company), but some generally available options are:

•Types of calls supported (voice, data, packetized data)

•Circuit-switched (dial-up) or permanent (nailed) lines

•One or two B-channels

•A telephone number for each B-channel, or one number for both channels

ISDN SWITCHES

The device controlling the ISDN line is the central office switch. It is usually owned by the network provider (e.g., the telephone company). Each switch has its own format and procedures for the D-channel protocols used to establish and control calls. (More on D-channel protocols later.) There are three main ISDN switch standards used in North America: AT&T, Northern Telecom (NTI), and NI-1. Their basic functions are similar, but each has its own set of special features and parameters.

Before using the TA, you must configure the unit for a switch type. The TA will operate with AT&T, Northern Telecom (NT), or any switch running National ISDN-1. Central Office (CO) switches can be loaded with different software versions. The TA supports AT&T switches running versions 5E4.2 and later, and NT switches running versions BCS29 and later.

UTA220/UTA220k 4-3