LET Integrated Services Digital Network (L-ISDN)
The LET Integrated Services Digital Network (L-ISDN) plug-in card has six ISDN circuits. The L-ISDN card transports the 2B+D data from the local exchange as three 64-kbps timeslots through the Tellabs 1000. At the remote terminal the R-ISDN recreates the physical 2B+D format for relay to the customer. The L-ISDN card utilizes mixed analog and digital signal processing circuit technology as described in TR-397.

Features and Benefits

  • Three (3) DS0 TDM
  • BER measurement with 2 thresholds
  • Supports 2B+D and B1+D configuration
  • Loopbacks as described in TR-397
  • Responds to ANSI EOC messages
  • Provides six, 2-wire DDS circuits
  • Can provide system timing
  • Six (6) ISDN circuits per card

Included Highlights

LED Indicators

The L-ISDN channel unit has three LED indicators on the faceplate. A green ACTV LED indicates the plug-in card is busy. A steady red FAIL LED indicates that the plug-in card has failed, and a fl ashing red FAIL LED indicates illegal signaling. An amber LOOP LED indicates the plug-in card is in loopback.

Six (6) ISDN lines.

Each L-ISDN plug-in card accepts six ISDN lines. It uses 2B1Q (2 binary 1 quaternary) line coding for full-duplex transmission at 144-kbps data rate. The transmission format delivers 12 kbps for synchronization, 144 kbps for 2B+D customer data, and 4 kbps for DSL overhead functions. The customer data is divided into two 64-kbps channels (B channels) and one 16-kbps channel (D channel).

Flexible Functionality

The L-ISDN plug-in card provides the interface towards the switch, including the DC termination of the sealing current. The L-ISDN card supports three (3) DS0 TDM and has built-in BER measurement.

Digital Data Service

The L-ISDN plug-in card supports 2-wire Digital Data Service (2w DDS). When deployed in a 2w DDS circuit, the counterpart R-ISDN plug-in card can emulate the 2B1Q (1B+D) Integrated Digital Subscriber Line (IDSL) signal.


  • Height: 5.125 inches (13.018 cm)
  • Width: 0.563 inch (1.429 cm)
  • Depth: 10.5 inches (26.67 cm)
  • Weight: 0.5 pound (0.23 kg)
  • Six (6) ISDN circuits per card
  • Typical power consumption: 5.5 W
  • Operating temperature: -40 F / -40 C to +149 F / +65 C
  • Humidity (relative): 5 to 95% non-condensing
  • TR-NWT-000393
  • TR-NWT-000397
  • Loopback modes: Equipment, Facility and DDS Latching
  • Line coding: 2B1Q
  • Data rate (throughput): 144 kbps
Faceplate LED Indicators
  • FAIL Red: Plug-in card failure, or card unable to communicate with the CPU
  • FAIL Flashing Red: Illegal signaling detected
  • ACTV Green: At least one circuit is active (busy) or supporting testing
  • LPBK Amber: A loopback is in progress
  • Tellabs Panorama Element Management System (EMS)
  • Craft User Interface (CUI)
Software Support
  • Minimum base software FP16 and higher
  • Supported in Tellabs 1000 MSAP CBA1120 and CBA1048
Analog Parameters
  • Equalization Transmit: 12.5 dB (2.5 Vpk)
  • Input impedance: 135 Ω ± 5%
  • Equalization Receive: x < 1.15 dB attenuation @ 40 kHz (0 – 2 kft. on 26 AWG wire)
  • Sealing current termination: 400 Ω
Product Specifications Sheet

LET Integrated Services Digital Network (L-ISDN)
Product Specifications
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