TN2198

DEFINITY Made Easy Tools
Issue 2, November 2000

DEFINITY Hardware

TN2198

The TN2198 allows connection to the ANSI standard 2-wire U-Interface. The 2-wire interface from the TN2198 connects to an NT1 network interface. The 4-wire interface on the other side of the NT1 may connect to 1 or 2 telephones. The TN2198 does not provide a trunk-side interface as does the TN2185 circuit pack.

The TN2198 contains 12 ports that interface at the ISDN U reference point. For each port, information communicates over two 64 Kbps bearer channels called B1 and B2, and over a 16 Kbps channel called the demand channel, or D channel. The D channel is used for signaling. Channels B1 and B2 can be circuit switched simultaneously. The D channel is always packet switched. The TN2198 requires a packet control circuit pack (TN778) on Category B ONLY. It is a dual coded, analog line 24-port, that performs all the functions of the TN746B, 16-port analog line circuit pack. Each port supports 1 voice terminal, such as 500 (rotary dial) and 2500 terminals (DTMF dial).

In a multiple terminal environment, the B channels are shared only on a per-call basis. For example, if the B2 channel is used for data, then the use of B2 by 1 terminal excludes the others from having access to it. When a device communicates over the D channel to access B1 or B2, that channel is owned until the call is taken (no party on line). The D channel is always shared among the terminals. The TN2198 interfaces with the TDM bus and packet bus in the DEFINITY backplane and terminates with 12 ISDN basic access ports.

The TN2198 has a long range to 18,000 feet (5486 m) maximum from the system to the NT1 device and uses standard protocol ANSI T1.601. The TN2198 has a 160 Kbps line rate, consisting of 2 bearer channels at 64 Kbps channels each, the D channel at 16 Kbps, framing at 12 Kbps, and maintenance at 4 Kbps. The circuit pack uses demand channel (ringing, tone, and so forth), 16 Kbps channel, and supports up to 24 telephones or data modules per circuit pack.

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