# Types of Registered Jacks (RJ45 & RJ11)

## Introduction to Ethernet Jacks

Ethernet jacks are essential components in networking, providing a **physical interface for data transmission** over wired connections. The two most common types are **RJ45** and **RJ11**, each serving distinct purposes in **computer networking, telecommunications, and VoIP systems**.

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## **What is RJ45?**

RJ45 (Registered Jack 45) is the **standard connector for Ethernet networking**. It supports **8 pins** and is used with **twisted-pair cables (Cat5e, Cat6, Cat7, Cat8)** for high-speed data communication.

### **RJ45 Features & Applications**
- **Used in Ethernet networks** (LANs, WANs, data centers).
- Supports **Gigabit (1Gbps) and multi-gigabit speeds (10Gbps, 40Gbps)**.
- Compatible with **shielded (STP) and unshielded (UTP) twisted-pair cables**.
- Utilizes **8-position, 8-contact (8P8C) configuration**.
- Found in **network switches, routers, access points, and PCs**.

### **RJ45 Pinout & Cable Color Codes**
RJ45 connectors follow **two wiring standards**: **T568A** and **T568B**.

#### **T568A Wiring Standard**
| **Pin** | **Cable Color** | **Purpose** |
|--------|----------------|-------------|
| 1 | White/Green | Transmit + |
| 2 | Green | Transmit - |
| 3 | White/Orange | Receive + |
| 4 | Blue | Unused (PoE Power) |
| 5 | White/Blue | Unused (PoE Power) |
| 6 | Orange | Receive - |
| 7 | White/Brown | Unused (PoE Power) |
| 8 | Brown | Unused (PoE Power) |

#### **T568B Wiring Standard**
| **Pin** | **Cable Color** | **Purpose** |
|--------|----------------|-------------|
| 1 | White/Orange | Transmit + |
| 2 | Orange | Transmit - |
| 3 | White/Green | Receive + |
| 4 | Blue | Unused (PoE Power) |
| 5 | White/Blue | Unused (PoE Power) |
| 6 | Green | Receive - |
| 7 | White/Brown | Unused (PoE Power) |
| 8 | Brown | Unused (PoE Power) |

**T568B is the most commonly used standard in modern Ethernet cabling.**

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## **What is RJ11?**

RJ11 (Registered Jack 11) is primarily used in **telecommunications** for telephone lines and **DSL broadband connections**. It supports **6 positions and 2 to 4 contacts (6P2C or 6P4C configuration)**.

### **RJ11 Features & Applications**
- Used for **landline phones, DSL internet, fax machines**.
- Supports **analog voice transmission**.
- **Smaller than RJ45**, only carrying **one communication line**.
- Can be inserted into an **RJ45 port**, but not vice versa.

### **RJ11 Pinout & Cable Color Codes**
| **Pin** | **Cable Color (2-Wire)** | **Cable Color (4-Wire)** | **Purpose** |
|--------|-----------------|-----------------|-------------|
| 1 | Not Used | Black | Additional Line (if present) |
| 2 | Not Used | Red | Additional Line (if present) |
| 3 | Green | Green | Tip (Primary Line - Positive) |
| 4 | Red | Yellow | Ring (Primary Line - Negative) |
| 5 | Not Used | Black | Additional Line (if present) |
| 6 | Not Used | Not Used | Unused |

**Pins 3 and 4 (Red & Green) are the primary pair used in standard telephone connections.**

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## **Key Differences Between RJ45 and RJ11**

| Feature | RJ45 | RJ11 |
|------------|------------------|----------------|
| **Size** | Larger (8P8C) | Smaller (6P2C or 6P4C) |
| **Pins** | 8 | 2 to 4 |
| **Use Case** | Ethernet networking | Telephone & DSL |
| **Cable Type** | Cat5e, Cat6, Cat7, Cat8 | Telephone wire |
| **Data Transmission** | High-speed internet | Voice communication |

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## **Conclusion**
RJ45 and RJ11 connectors serve **different purposes**, with RJ45 dominating **computer networking** and RJ11 being used in **telephony and DSL internet**. Understanding their wiring standards and configurations ensures proper installation and functionality in **both home and commercial environments**.