RJ45 Breakout Cable for Multi-line Analog Phone System



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A multi-line analog phone RJ45 breakout cable can take a single RJ45 connection with multiple analog phone lines and break them into individual connections or take multiple phone lines and combine them into one RJ45 connection.

In this following scenario, we have two analog phone lines wired to two individual RJ45 female connectors in a network rack. The following guide will walk you through the creation of an RJ45 breakout cable designed to take the 2 analog phone lines and transmit both lines across a single RJ45 connection for a multi-line analog phone.

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Step 1: Understanding the Technology

Patch cables

Network patch cables will follow the TIA/EIA 586 wiring standard as shown above. Typically, patch cables will use the T586B standard, but always verify the patch cable's color code.


For this project, you should be aware of two types of connectors: RJ45 and RJ11.

RJ45 connectors are primarily used for network cables and contain 8 contact points. These connections are often refereed to as 8P8C (8 Position 8 Contact). Typically, an RJ45 connection will use all 8 wires of a Cat5, Cat5e, or Cat6 cable. For this project, we will be using RJ45 connectors to collect analog phone lines that only use 2 contacts.

RJ11 cables will have 6 positions, but only use up to 4 conductors (6P4C). This type of cable can handle two different analog phone lines simulations. An RJ11 cable with 2 conductors (6P2C) can only handle a single analog phone line.

When an RJ11 cable is plugged into a female RJ45 connector, the center pins will line up. The above diagram shows which pins will connect between an RJ11 cable and an RJ45 connector.


The above wiring diagram shows which lines from the Cat5e patch cable will be used for each phone line. Pins 4 & 5 are used for the first line and pins 3 & 6 are used for the second line. For this specific project, the phone lines running into the building are wired to 2 separate RJ45 connectors that use pins 4 & 5.

The patch panel was wired so that a phone can be plugged directly into the patch panel. We will make a patch cable that allows a 2-line analog phone to be plugged directly into a single RJ45 connector in an office and be patched to the correct phone lines.

Under most circumstances, the analog phone lines in a network patch panel will be wired as shown in this guide. However, always verify what standards and configurations were used during installation.

Step 2: Gather Materials

You will need the following:

- Cat5e patch cable

- RJ45 male connectors

- RJ45 crimpers

- RJ45 cable tester

- Clippers or Electrician scissors

Step 3: Prepare the Patch Cable

Start by clipping the head off of the Cat5e patch cable and stripping off the outer jacket, as shown above.

Strip the patch cable enough to allow each pair to reach their designated spot on the patch panel. The image above shows the patch cable stripped to 2".

Clip off the unneeded pairs - Orange and Brown.

Step 4: Create the First Connector

Untwist the end of the blue pair and insert the blue wire into pin 4 and the white / blue wire into pin 5 of the RJ45 connector. You want the wires to keep their twist as much as possible.

Using the RJ45 crimper, insert the connector into the proper hole and squeeze the handles of the crimping tool, as shown above.

Step 5: Create the Second Connector

Untwist the end of the green pair and insert the white / green wire into pin 4 and the green wire into pin 5 of the RJ45 connector. You want the wires to keep their twist as much as possible.

Using the RJ45 crimper, insert the connector into the proper hole and squeeze the handles of the crimping tool.

Step 6: Test the Cable

Using an RJ45 cable tester, test the blue pair connection. You should see pins 4 & 5 connected with the tester.

Test the green connection. You should see pins 3 & 6 connected with the tester.

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