This Configuration Guide describes the configuration steps for Cox SIP Trunking with the Cisco Unified Communications Manager (CUCM) 7.1.3(b) and the Cisco Unified Border Element (CUBE) for connectivity to Coxâs SIP Trunking service.igure 6 â Terminating Call Flow Overview. The Incoming call flow is: PSTN ï  Coxâs SIP Network ï  Cox E-SBC ï  CUBE ï  CUCM. In the lab example, a test account DID ranges were created for Cisco Unified Communications Manager. interoperability certification: Site 1: 678.239.