T-1 Monitor and Tap

T-1 Monitor and active tapping device


  • Actively monitor T1 lines
  • Actively repeats the T1 signals
  • RJ48 or screw down connectors
  • Simple connection to 4-wire circuits
  • 120/240 VAC, 12, 24, 48, or 125 VDC available
  • 1U high rack mountable, 1, 2, or 3 x 19” rack
  • 20 slot rack chassis option
  • DIN mount option
  • Ideal for lawful intercept and CALEA
  • Use for quality monitoring and SS7 extraction

RJ-45 adapters or screw terminals may be used in all ports.

Unit supplied with two screw terminals,
one Telco Demarc RJ-45 and one CPE RJ-45 adapter.




Download the Manual (PDF version)

Application Notes


Installation Accessory Kit

How to order



The DCB T-Monitor uses 4-wire repeater technology to provide a monitor point for T1 or E1 lines. The T-Monitor is based on the field proven DCB T-Extender. The T-Monitor uses repeater circuits on all data paths. This active repeater function is superior to simple passive monitor devices. For some T1 and E1 circuits, the double termination of passive monitor devices will attenuate the signal enough to generate data errors. The T-Monitor units are the solution to this attenuation problem. The Monitor units provide both electrical isolation and actively repeat the signal.

The circuitry is rated to -36 dB dynamic range at the T-1 rate of 1.544 Mbps. Solid copper 22 AWG, two twisted pair is the preferred cable for connection between the units, and all T1 equipment (We do not recommend CAT5 cable). Connection to the Monitor is made through RJ48(RJ-45) modular connectors or 4-wire screw down barrier strips. Each Monitor comes standard with three screw down barrier strips and two RJ48 connectors. If only RJ48 connections are desired extra RJ48 adapters (part number 9502122 to connect to telco, 9502172 to connect to customer equipment) may be ordered.

The DCB T-Monitors are normally powered by a small wall-mount transformer. Power supply options include 120/240 VAC, 12, 24, 48 or 125 VDC. Rack mount options include a 1U 3-unit shelf and a 20 slot rack.

The T-Monitors are transparent to the type of data sent over the T-1 link. The data can be D-4 format,AMI, ESF, PRI, etc.


T-1 Monitor
Actively repeats T1 bi-polar signals
DSX-1 interface
Recommended Cable
Two twisted pair solid copper 22 or 24 AWG; standard telco T1 cable if UTP category rated cable is used, CAT 3 is recommended.
We do NOT recommend CAT 5 cable. Although it often works well, CAT 5 cable has been shown to cause problems with many T1 installations.

Front panel power LED
  • RJ45 wiring adapter p/n 9502122 to connect to Telco (demarc) using straight through cables.
  • RJ45 wiring adapter p/n 9502172 to connect to customer equipment (CPE) using straight through cables.
  • Customer to demarc RJ45 cable p/n 9500095
  • Rack shelf, 1 U for 1 to 3 T1 Monitors
  • 20 slot, 4U high 19" rack mount chassis
  • Din clip mount, spring mount, P.N 6013006
    5.5" x 7.5" x 1.5" 100 ohm T1 DSX-1 interface 2 lbs including wall transformer 120 VAC external wall transformer supplied Optional 240 VAC, 12, 24, 48, 125 VDC options available 30 ma -40 to +70 C operating temperature Operating Humidity: < 95% non-condensing

    Installation Accessory Kit

    Many technicians installing T-Monitors for the first time don't have all the cables required to cable up a unit and show that the T-1 line and other equipment operates properly on a work bench, or in the telephone closet. This kit includes all the parts needed to install the T-Monitor and the CPE within reach of the telephone company demarc and run short cables to the monitor device, as well as a physical loopback RJ-45 plug to use diagnosing any problems that occur. Parts included are three T-1 straight-through cables, two RJ adapter boards (one CPE and one Demarc), and one T-1 RJ loopback plug.

    Application Note

    T-1 Cables and Cross-Talk We receive many questions about what kind of cable works best for T-1 installations. Many people mistakenly believe Cat-5e or Cat-6 LAN cable works well. Here's the scoop... a technical discussion about why you should use real T-1 cable for every T-1 installation, and some manufacturer's part numbers. T-1 Cables and Cross Talk



    One RJ-45 connector and two screw terminal connectors are included with each T-Extender.
    Item Number Description Price Buy Now!
    T-Monitor T-1 Line monitor w/ 120VAC power input $ 595 Qty:
    T-Monitor/12VDC T-1 Line monitor w/ 9-18 VDC power input $ 670 Qty:
    T-Monitor/24VDC T-1 Line monitor w/ 19-36 VDC power input $ 670 Qty:
    T-Monitor/48VDC T-1 Line monitor w/ 36-72 VDC power input $ 670 Qty:
    9501030 External 125 VDC power supply for standard T-Monitor $ 125 Qty:
    9500095 T-1 RJ45 straight through cable $ 12 Qty:
    9500099 T-1 RJ45 crossover cable $ 12 Qty:
    9502122 Additional RJ adapter $ 12 Qty:
    9502172 Additional RJ adapter $ 12 Qty:
    5003011 Additional screw terminal adapter $ 12 Qty:
    TMON-KIT T-Monitor installation accessory kit $ 49 Qty:
    9500106 T-1 loopback plug, RJ-45/48C $ 5 Qty:
    9902095 19" rack shelf for 1 to 3 T-Monitors $ 75 Qty:
    L-1 20 slot 19" rack chasis $ 1,500 Qty:

    Data Comm for Business Inc.
    2949 County Road 1000 E
    Dewey, Il 61840
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    Toll Free: 800-4-DCB-NET
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    Email: Contact Page
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    Fax: 217-897-8023
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