LOOP-T 2500
Single and Dual Port CSU/DSU


  • DSU functionality integrated with an intelligent CSU in a compact package
  • Single or Dual DTE port models
  • T-1, Router, V.35, EIA-530, RS-232, RS-449 Interfaces
  • SNMP Management or terminal console port
  • GUI Windows based management system available
  • Connection to LAN/WAN, CAD/CAM, or Hosts to T1 Network Services
  • 2-line by 16-character LCD
  • Compliance with ANSI T1.403-1989, AT&T TR 54016, 54019, 45019A and 62411, FCC Part 15 Class A, FCC Part 68, DOC-CS-03, CSA 22.2 No. 225, UL 1459
LT500SA picture

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Loop Telecom's Loop-T2500 FT1 CSU/DSU series provides an economic solution to T1 network access cost, when a full T1 or fractional T1 of some DS0 channels is needed. This product series support Extended Superframe Format (ESF) which makes possible continuous error checking, performance polling, and in-service diagnostics. Customer equipment interfaces include T1, series DTE, and Router. With DTE port operating from 56 to 1536 Kbps, Loop-T2500 FT1 CSU/DSU allows users to interconnect LANs and WANs, CAD and CAM, video conference, mainframe hosts, and others.

Loop-T2500 FT1 CSU/DSU series support local control and diagnostics using 2-line by 16-character LCD display and keypads or RS232 console port. This allows users to execute in-service diagnostics and fault isolation. The multi-colored LEDs on the front panel provide both line side and DTE side status indicators. An in-band management channel with GUI are available. Using SNMP Network Management Systems or Telnet connection, users can remotely control and diagnose Loop-T products from anywhere. A GUI Windows based SNMP manager, LoopView, is available.

DCB is the North American Warranty Repair Station for all Loop products!


Network Line Interface (DS-1 Interface)
Line Rate

1.544 Mbps ± 50 bps


D4 / ESF (selectable)

Line Code

AMI / B8ZS (selectable)



Input Signal

DS-1 form 0 dB to -26 dB w/ALBO

Output Signal

DS-1 w/ 0, -7.5, -15 dB LBO

Surge Protection

FCC Part 68 SubPart D

Pulse Template

Per AT&T TR 62411

Customer Equipment Interface

A. Single or Dual DTE Data Ports

B. DS0 Mapping

Data Rate

N * (56 or 64) Kbps (n = 1- 24)


2 sets of DS0 map with provision for


V.35: M34,DB-25
EIA-530: DB-25
RS-232: DB-25
LAN: 100BaseT

automatic switching between the 2 maps

Remote Send

Send active DS0 maps to remote site (in ESF mode only)

Performance Monitor

Performance Memory

The last 24 hours performance in 15-minute intervals line, user, and remote site (in ESF mode only)

Performance Reports

Report includes Date & Time, Errored Second, Unavailable Second, Bursty Errored Second, Severe Errored Second, Controlled Slip Second, and Loss of Frame Count.

Alarm History

Report includes Date & Time, Alarm Type (i.e. Master Clock Loss, Yellow Alarm, AIS, LOF, BPV, ES, CS), and Location (i.e. line, DTE).

Alarm Queue

Contains 40 alarm records which record the latest alarm type, and date & time


ANSI T1.403 PRM (Performance Report Messages) (selectable)

System Configuration Parameters (All in non-volatile memory)

Active Configuration

Current working configuration

Stored Configuration

User stored configuration

Default Configuration

Manufacture default configuration (permanent)

Console Port


RJ-11 at Front Panel


RS232 interface


Menu driven VT-100 terminal, SLIP, or Embedded SNMP (optional)

Diagnostics Test


Line Loopback, Payload Loopback, Local Loopback, and DTE Loopback

Test Pattern

20 bits QRSS, 3-in-24, 1-in-8, 2-in-8, 1:1 patterns

Idle Channel

Use of idle channel to perform QRSS diagnostic test

Remote Loopback

AT&T inband Loopback & Payload Loopback, ANSI Line Loopback, Payload Loopback

DTE Channel Loopback (ANSI T1.403 Annex B or Loop proprietary)

Front Panel


4 keys: left arrow, right arrow, ESC, and ENTER >


2-line by 16-character LCD





8 ½ " x 2 ¼ " x 11 ¼ " (WxHxD)


20-60 Vdc, 90-250Vac, 5 Watts

Temperature range



0 - 95%RH (non-condensing)


Desk-top stackable, 19/23 inch rack mountable


AT&T TR 54016, AT&T TR 54019, AT&T TR 54019A, AT&T TR 62411, ANSI T1.403-1989, FCC Part 15 Class A, UL1459, CSA 22.2 No. 225, FCC Part 68, UL 1459, DOC-CS-03

How to Order

To specify options, substitute:
DTE = 11 for V.35 DTE interface with M-34 connector
DTE = 22 for V.35 DTE interface with DB-25 connector
DTE = 22 for V.35 DTE interface with DB-25 connector
DTE = 33 for EIA530 DTE interface
DTE = 44 for X.21 DTE interface
DTE = 55 for RS-232 DTE interface
DTE = 66 for RS-449 DTE interface via conversion cable
pp = DC for 20-60 Vdc power source
pp = AC for 90-250 50/60 Hz Vac source
TA-2500-2S-DTE-SNMP-pp 1 Port DTE Interface T-1 DSU, SNMP $ 498
TA-2500-2S-RT-SNMP-pp 1 Port Router Interface T-1 DSU, SNMP $ 625
TA-2500-2S-T1-SNMP-pp 1 Port Single T1 Interface T-1 DSU, SNMP $ 535
TA-2500-2S-CD-SNMP-pp 1 Port Co-Directional Interface T-1 DSU, SNMP $ 542
TA-2500-2S-DTE-DTE-SNMP-pp 2 Port (DTE + DTE) Interface T-1 DSU, SNMP $ 582
TA-2500-2S-RT-DTE-SNMP-pp 2 Port (RT + DTE) Interface T-1 DSU, SNMP $ 709
TA-2500-2S-T1-DTE-SNMP-pp 2 Port (T1 + DTE) Interface T-1 DSU, SNMP $ 620
TA-2500-2S-T1-RT-SNMP-pp 2 Port (T1 + RT) Interface T-1 DSU, SNMP $ 747
TA-2500-2S-T1-T1-SNMP-pp 2 Port (T1 + T1) Interface T-1 DSU, SNMP $ 658
TA-2500-2S-RT-RT-SNMP-pp 2 Port (RT + RT) Interface T-1 DSU, SNMP $ 836
TA-2500-2S-CD-CD-SNMP-pp 2 Port (CD + CD) Interface T-1 DSU, SNMP $ 672

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