# Phone jacks: RJ11, RJ14 and USOC terminals

Recognize telephone connector families and a documented screw-terminal conversion.

**Applies to:** The conversion below is for the cited Leviton G/R/Y/B telephone wallplates. Handsets, digital PBX ports and country-specific cords may differ.

## When to use it

Identifying an analog telephone wall jack and its pair labels.

## Why it works this way

Connector contact count and service wiring are different things: RJ11 is one line, RJ14 two, and RJ25 three.

![Phone jacks: RJ11, RJ14 and USOC terminals — The conversion below is for the cited Leviton G/R/Y/B telephone wallplates. Handsets, digital PBX ports and country-specific cords may differ.](https://valleytech-black-wire-guide.pages.dev/library/wiring/telephone-jacks.svg)

[Open / save the original SVG](https://valleytech-black-wire-guide.pages.dev/library/wiring/telephone-jacks.svg)

## Connection reference

| USOC terminal | T568A conductor | T568B conductor |
| --- | --- | --- |
| G / green | White/blue | White/blue |
| R / red | Blue | Blue |
| B / black | White/orange | White/green |
| Y / yellow | Orange | Green |

## Make the connection

1. Record existing terminal labels and identify the service before changing wiring.
2. Use the matching manufacturer's terminal map and check cable continuity while disconnected.

## Check before powering

- A live telephone line is not a GPIO-level signal; never connect it directly to a microcontroller.
- A telephone plug fitting a larger socket does not establish electrical compatibility.

## Matching module references

This is a general interface guide; match your own hardware documentation.

## Sources & review

Source documents inspected; independent electrical and bench review pending. Reviewed 2026-09-27.

- [Leviton telephone wallplates, PK-93298-10-02-0H](https://leviton.com/content/dam/leviton/network-solutions/product_documents/instruction_sheet/Leviton-IST-Telephone-Wallplates.pdf) — Page 1: USOC to T568A/B conversion; G/R/Y/B screw terminals; checked 2026-09-27
- [Fluke Networks: RJ connector naming](https://www.flukenetworks.com/blog/cabling-chronicles/history-rj45-case-mistaken-identity) — RJ11 / RJ14 / RJ25 versus modular connector contact counts; checked 2026-09-27

Original writing and diagram by Kal / Valleytech Solutions, CC BY 4.0. Manufacturer artwork and documentation retain their own rights.

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