Explanation
n Contact Center Enterprise with Cisco Unified Customer Voice Portal (CVP) and Cisco Unified Border Element (CUBE) deployment, CUBE must be configured as media pass flow-through mode. This means that CUBE will terminate and reoriginate both the signaling and media streams for each call leg. This allows CUBE to perform media manipulation, such as transcoding, transrating, DTMF interworking, and media forking. Media pass flow-through mode is required for CUBE to support advanced features for contact center, such as courtesy call back, contact center survivability, and encrypted (SRTP) trunks. Media pass flow-around mode, where CUBE only terminates and reoriginate the signaling stream and lets the media stream bypass CUBE, is not supported for contact center solutions. A voice gateway must not be dedicated for VXML browser sessions, as CUBE can coexist with VXML gateway on the same platform. Box-to-box CUBE can be used for redundancy, but it is not a mandatory configuration for contact center solutions123. References:
Cisco Unified Border Element Configuration Guide - Cisco IOS XE 17.6 Onwards - Advanced Features for Cisco Contact Center2 Cisco Unified Border Element (Enterprise) Fundamentals and Basic Setup4 Cisco Unified Border Element for Contact Center Solutions5