What is the name of the SIP interface between a PBX and an ITSP?

The interface between a PBX (Private Branch Exchange) and an ITSP (Internet Telephony Service Provider) is commonly known as a SIP Trunk. This connection allows the PBX to initiate and receive voice calls over the Internet using the SIP protocol. SIP Trunks enable businesses to take advantage of VoIP (Voice over Internet Protocol) services for telecommunications, offering flexibility and cost efficiency compared to traditional phone lines.

The correct designation of this method is crucial; it highlights the role of SIP Trunks in facilitating the transmission of multiple concurrent calls over a single broadband Internet connection. Furthermore, SIP Trunks allow various features such as scalability, reduced operational costs, and convergence of voice and data networks.

Understanding the function and importance of SIP Trunks is essential for anyone involved in managing voice communications and network infrastructure, particularly in a modern, cloud-based telephony environment.