Name one type of SIP server.

A Proxy Server is one type of SIP server, playing a crucial role in session initiation protocol (SIP) communications. Its primary function is to relay SIP messages between clients, enabling them to establish and manage sessions such as voice calls, video conferencing, or messaging. Unlike other server types, which perform specific storage or data retrieval functions, a Proxy Server is designed to facilitate the flow of SIP traffic, ensuring that requests and responses between callers are correctly routed. This capability is essential for handling signaling messages, maintaining security, and enabling features like authentication and registration within SIP infrastructures. Therefore, the Proxy Server is integral for a seamless and efficient SIP communication experience.