The **RJ11 (Registered Jack 11)** is a standard telecommunication connector used primarily for connecting telephone equipment. It is the most common interface for analog telephone lines worldwide. --- ## 1. Physical Structure and Components A standard RJ11 plug consists of the following electronic and mechanical parts: | Component | Description | Material | | :--- | :--- | :--- | | **Housing** | The clear outer shell that holds the pins and cable. | Polycarbonate (Thermoplastic) | | **Contacts/Pins** | The conductive metal parts that interface with the jack. | Phosphor Bronze with Gold Plating | | **Locking Tab** | A flexible lever that snaps the plug into the socket. | Plastic (integrated into housing) | | **Crimp Area** | The rear section where the cable jacket is secured. | Plastic | --- ## 2. Technical Specifications The RJ11 is often confused with other RJ connectors. Here are its specific technical attributes: * **Configuration:** **6P2C** or **6P4C**. * *6P:* 6 Positions (slots for pins). * *2C/4C:* 2 or 4 Contacts (actual metal pins loaded). * **Dimensions:** Approximately 9.6mm in width (narrower than RJ45). * **Gold Plating Thickness:** Usually measured in micro-inches (e.g., 3µ", 15µ", 50µ"). Higher thickness prevents corrosion and improves conductivity. --- ## 3. Pinout and Wiring (6P4C Standard) In a standard 4-wire RJ11 setup, the wires follow a specific color code and function: | Pin Number | Color (Old Standard) | Color (New/Cat) | Function | | :--- | :--- | :--- | :--- | | **1** | White | White/Orange | Unused / Reserved | | **2** | **Black** | **Blue** | Tip (Line 2) | | **3** | **Red** | **White/Blue** | Ring (Line 1 - Primary) | | **4** | **Green** | **Green** | Tip (Line 1 - Primary) | | **5** | **Yellow** | **White/Green** | Ring (Line 2) | | **6** | Blue | Orange | Unused / Reserved | > **Note:** For a single-line telephone, only the center two pins (Red and Green) are required to complete the circuit. --- ## 4. Electrical Characteristics * **Voltage:** Typically carries **48V DC** (on-hook). During a "ring" event, an AC voltage of approximately **90V** is superimposed. * **Current:** Low amperage, typically around **20mA to 50mA** during active calls. * **Contact Resistance:** Generally less than **20mΩ**. ---