Explanation
Cisco Unified Border Element (CUBE) is a session border controller that provides session control, security, interworking, and demarcation for voice and video calls between the enterprise IP network and service provider SIP trunks1. When CUBE is used with CCE and CVP, it provides the following three features:
Silent Monitor inbound voice calls: CUBE supports the silent monitoring feature for inbound voice calls from the PSTN to the CCE agents. This feature allows supervisors to listen to the agent-customer conversations without being noticed by either party. CUBE uses the built-in-bridge (BIB) capability of the agent phone to fork the media stream and send it to the monitoring server2.
Secure communication using flow around mode: CUBE supports secure communication using Transport Layer Security (TLS) and Secure Real-Time Transport Protocol (SRTP) for SIP signaling and media streams. CUBE can operate in flow around mode, where it terminates the TLS/SRTP sessions from the service provider and the enterprise, but does not perform any media processing or transcoding. This mode reduces the CPU load on CUBE and preserves the end-to-end media encryption3.
Normalize SIP messages using SIP profiles: CUBE supports SIP normalization using SIP profiles, which are collections of parameters that modify the SIP messages that pass through CUBE. SIP profiles can be used to resolve interoperability issues between different SIP implementations, such as service providers, CVP, and CCE. SIP profiles can also be used to enhance the functionality of CUBE, such as adding or removing headers, modifying timers, and enabling features4.
References: Cisco Unified Border Element data sheet1, Cisco Unified Border Element Configuration Guide234.