Convert Single Cat 5e into Ethernet and Phone

How to convert a single Cat5e connection into an Ethernet & Phone line

My new home was prewired with Cat5e cable for telephone. While this is nice, I didn’t want to be tied down to phone-only mainly because I prefer to have the option of placing my wireless router on the 1st story in order to have a stronger signal on both the 1st and 2nd story, and when I’m outside in the backyard so I can bump Spotify while mowing the lawn and not chew up my data plan.

Here’s how I converted the phone line that ran into my office into both Ethernet and phone:

Shopping List:

I purchased the following from

To begin, remove the RJ11 wall plate.

Once removed from the wall, you’ll see which twisted pair of copper wire are connected to the jack of the wall plate. There are two standards of wiring called T568A and T568B, where the recommended standard for residental dwellings based on the “Residential Telecommunications Cabling Standards” is T568A, which I assumed the builder has followed. Here are two diagrams depicting these two standards:

Figure 1: View of wired Ethernet connector, showing cable layout for each standard

Figure 2: another diagram from wikipedia showing Pin to Pair mapping per standard

In my case, Pair 1 & 2 were being used for telephone, which left Pair 3 & 4 unused. Here is a picture of what mine looked like:

You can see the white/orange, orange, white/blue, blue cables connected to the screws on the plate.

These same cables (Pair 1 and Pair 2 per the T568A standard) will be used in the new Cat3 RJ11 adapter (first bullet point item of shopping list) by simply removing them from the wall plate, and inserting them into the respective punch down slots of the adapter . Be sure to insert them into the same color code on the RJ11 adapter as it was on the wall plate. (You may have noticed the wall plate also has color coded wiring). Before I removed the cables from the wall plate, I wrote down the color mapping just in case (see image below), where the / represents the color white (ie “orange/“ means White/Orange).

Here’s a diagram to illustrate what it should look like, and we can see it matches up with what I’ve written down:

Pins 2,3,4,5 are the pin outs for phone on the RJ11 adapter. These pin numbers are clearly labeled on the adapter just as they are color coded (per the handwritten mapping).

Note: here is a picture of my setup below. In this picture below, I installed the wires into the adapter, tested to make sure it worked, then snapped the adapter into the Keystone 2 port wall plate.

Now for the Internet

In my experience of making cables, I’m used to the T568B standard. You can confirm this yourself by looking at the tip of a network cable (see Figure 1 above) and see that the color of the wires within are in the Pin positions shown in the T568B diagram above. With that said, the Pin Position is what will be important when making the connection for Ethernet since electronically, cable color doesn’t matter. Just don’t confuse yourself like I did since Pair 1 and Pair 2 per T568A (the white/blue blue and white/orange orange) cables are already used.

In this case, I referenced T568B and I opted to turn the White/Brown Brown pair into pin positions 1 and 2 to serve as Pair 2 (the White/Orange Orange pair) in the T568B standard, and White/Green Green pair into pin positions 3 and 6 to serve as themselves in Pair 3.
I probably should have kept in the T568A standard and left Pair 3 (White/Green Green) to the pin 1 and pin 2 position. Again doesn’t really matter as long as the correct pin positions for an Ethernet connection have a wire and match on the other end.

Go into the basement and find the Cat5e cable that runs into the room where you want to convert into phone & Ethernet. Using a RJ45 connector and the crimpers, carefully insert the twister pairs into their respective Pin out locations. Be sure they are pressed firmly to the tip of the connector and remain there as the connector is crimped.

This is well depicted in the image below where you will see Pair 4 (white/brown brown) in the Pin 1 and Pin 2 position, and Pair 3 in Pin 3 and Pin 6 position.

Plug this end into your DSL or cable modem:

Go back into the room where you want to make two connections. Grab the RJ45 adapter you purchased from the shopping list and following the numbers on the adapter, put the cables into the numbered Pin positions, just as you did with the basement connection:

Test the connection to make sure it works. If it does, then you’re done! Cut the ends on the outter side of the adapter and button everything up and you’re wall plate should look like this!


I think the phone only requires one pair (at least it did in my last house), so I could have tested by using the T568A standard to wire things up as follows:

  • Phone
    • Pair 1 -> White/Blue Blue -> RJ11 adapter punch down slots 4 & 3 respectively
  • Ethernet
    • Pair 3 & Pair 2 -> White/Green Green, White/Orange Orange -> RJ45 adapter punch down slots 1,2, 6,3 respectively

If I change another outlet in the house, I will likely try it this way, and take more pictures to better illustrate the process. This would leave pair 4 unused.

One other note is that as long as your home won’t be using 1 GBps connections, then it’s possible to split the twisted pair of one cable for phone and Ethernet. Otherwise, if your home will require 1 GBps (1000MBps) connections, then this cannot be accomplished since 1 GBps connections require all 4 sets of the twisted pair.