Signaling System No. 3 (SS3) is a telecommunications protocol used primarily in the public switched telephone network. It facilitates the exchange of information between different network elements, such as switches and databases, ensuring efficient call setup, management, and teardown. SS3 is essential for handling signaling messages, which are crucial for establishing and maintaining telephone calls. This system operates over a packet-switched network, allowing for faster and more reliable communication compared to older signaling methods. It supports various services, including caller ID, call forwarding, and mobile roaming, enhancing the overall functionality of modern telecommunication systems.