Use Invoice2go with SIP

Session Initiation Protocol (SIP) is a communications protocol that is widely used for managing multimedia communication sessions such as voice and video calls. SIP, therefore is one of the specific protocols that enable VoIP. It defines the messages that are sent between endpoints and it governs establishment, termination and other essential elements of a call. SIP can be used to transmit information between just two endpoints or many. In addition to voice, SIP can be used for video conferencing, instant messaging, media distribution and other applications. SIP has been developed and standardized under the auspices of the Internet Engineering Task Force (IETF).