Enterprise session border controllers (E-SBCs) are situated at the edge of the enterprise network and provide secure voice and video connectivity to Session Initiation Protocol (SIP) trunking providers, users in remote branch offices, home workers/remote workers, and unified communications as a service (UCaaS) providers. The name 'session border controller' is derived from the following: Session, from Session Initiation Protocol, refers to a real-time communication connection between endpoints or users. This is typically a voice and/or video call. Border refers to the interface between networks that do not have full trust of each other. Controller refers to the ability of the E-SBC to control (allow, deny, transform, end) each session that traverses the border. The 'E' in E-SBC stands for 'enterprise.' It is intended to differentiate enterprise-focused SBCs from those aimed at carriers.