How are SIP and RTP related?

SIP, which stands for Session Initiation Protocol, is a signaling protocol that establishes, modifies, and terminates multimedia sessions such as voice and video calls over the Internet. It is responsible for setting up the session and handling the communication parameters, such as the locations of the participants and the types of media to be used.

RTP, or Real-time Transport Protocol, on the other hand, is specifically designed for the transport of audio and video across IP networks. It provides the means to transmit media streams and is optimized for the delivery of real-time data, ensuring that the data packets arrive timely and are played back in the correct order.

Therefore, the correct relationship between SIP and RTP is that SIP is used for signaling, meaning it aids in the setup and management of the session, while RTP takes over once the session is established to transport the actual media content. This delineation highlights how SIP and RTP complement each other to facilitate effective communications, with SIP handling the parameters and setup while RTP focuses on transmitting the media itself.