Knowledge Base

The Digium Knowledge Base is a searchable library of troubleshooting advice and current information updated by Digium support technicians.
Search:     Advanced search
Browse by category:
Contact Us
Knowledge Base / Hardware / Products / Digital Interface Cards / How do I make an E1/T1 loopback connector?

How do I make an E1/T1 loopback connector?
Views: 11723, Votes: 7

Posted:
26 Apr, 2006 - Support D.

Updated:
05 Nov, 2008 - Support D.
Print Email article
Building a T1/E1 Loopback Connector.

In order to perform a loopback test of the E1/T1 port, a loopback plug (also known as loopback connector or loopback cable) is needed. An E1/T1 loopback connector can easily be made using a single RJ45 connector and two 4-in (10-cm) wires.

Materials Needed:

  • Unused RJ-45 plug
  • Two strands of Category 5 (Cat-5) wire, each 4-in (10-cm) long
  • Crimp tool for RJ-45
RJ45 Plug
Figure 1: RJ45 Plug

Procedure:

  1. Insert one end of wire 1 into pin 1 of the RJ45 connector. Note: To ensure a good connection, make sure that each wire goes all the way into the end of the plug. Refer to Figure 1 for an example of an RJ45 pin layout.
  2. Insert the other end of wire 1 into pin 4 of the RJ45 connector.
  3. Insert one end of wire 2 into pin 2 of the RJ45 connector.
  4. Insert the other end of wire 2 into pin 5 of the RJ45 connector.
  5. Crimp the connector.
Now you have a small loopback cable: a single RJ45 connector with pin 1 connected to pin 4, and pin 2 connected to pin 5.

After you install the loopback cable, zttool (or dahdi_tool) should show the span status as "OK" (green LED) on that specific span. If the status of that specific span is not "OK", then the E1/T1 loopback cable was made incorrectly (try another loopback cable), or the port is defective.
Other articles in this category
document I am hearing an echo. What can I do to fix this?
document How do I install Zaptel on a machine running Debian?
document How do I setup caller ID?
document How do I install the Zaptel drivers on a system running Fedora Core?
document Asterisk does not properly detect when a caller hangs up the phone. How do I fix this?
document How do I install Zaptel drivers on a system running Redhat?
document When will the LED's light up on my TDM400P/TE110P/TE2XXP/TE4XXP?
document What kind of cable do I use to connect to a channel bank?
document Do I need a sound card for music on hold or voicemail?
document Which pins of the crossover cable are for TX- TX+ RX- RX+?
document Where can I find a motherboard with 3.3 volt slots for the TE410P/TE411P/TE210P card?
document What kernel modules are used for which piece of Digium hardware?
document Why do I hear echo when I make a call?
document What are the differences between FXS and FXO interfaces?
document What is the difference between loopstart, groundstart, and kewlstart signalling?
document I'm using Cybiolink P-1 ADSI analog phone with Asterisk. Unfortunately sometimes when I make a call Asterisk doubles or skips some DTMF's resulting in a wrong number. Can you help ?
document I am unable to break dialtone with a channel bank and a T1 card.
document I have two cards: E100P and T100P (E400P and T400P). How can I tell which one is E1/T1 ?
document How do I install Digium's T1/E1 cards?
document I have E100P and T100P cards in my box. How can I know which one was loaded first ?
document I have two E100P cards in my box. How do I determine which one was loaded first ?
document I have TE410 and want to use it with 24 FXS T1 channel band and 8 FXO/16 FXS T1 channel bank and two E1 spans. How do I configure the config files ?
document What do I do if I can't compile Zaptel package on my system ?
document How do I connect a channel bank to my T1/E1 card?
document How do I configure Digium's T1/E1/J1 cards?
document Why does modprobe hang while loading a Zaptel kernel module?
document How do I fix echo over VoIP when a Digium card is in the call path?
document Why is my card getting an IRQ miss?
document Why do I get an NMI error?
document Why am I getting dropped calls?
document Why am I getting phantom rings?
document Why am I having DTMF detection problems?
document Why is there a pause after the last DTMF digit?
document Why am I not getting a dialtone using a channel bank and a T1 card?
document Why is my handset not ringing?
document Which certifications has the TE411P received?
document Which certifications has the TE410P received?
document Which certifications has the TE406P received?
document Which certifications has the TE405P received?
document Which certifications has the TE110P received?
document How do I set the Dual/Quad span card in T1/E1 mode?
document How do I configure multiple Dual/Quad span cards in same machine?
document Is my T100P still under warranty?
document Is my E100P still under warranty?
document I'm using E&M Wink channels on a T1/E1 line and Asterisk is not getting the correct CallerID or DID numbers. What is the problem?
document Is my T400P still under warranty?
document Is my E400P still under warranty?
document How do I troubleshoot problems over email with Digium's Technical Support staff?
document I am getting error messages about PCI Master Aborts. What is wrong?
document I can't find the TE411P for sale on Digium's site. Why is that?
document I can't find the TE406P for sale on Digium's site. Why is that?
document How do I run a pattern loopback test (patlooptest) on my E1/T1 card?
document Does the B410P provide Zaptel timing?
RSS Powered by KBPublisher (Knowledge base software)