This document describes the Session Initiation Protocol (SIP) and the Customer Voice Portal (CVP) call flows.
Cisco recommends that you have knowledge of these topics:
CVP Call Server
The information in this document is based on CVP Server 9.0.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.
CVP SIP Components Communication
CVP Web Application is the overall container for CVP, with the SIP Business to Business User Agent (B2BUA) which operates as a component within this process. All SIP call control messages occurs among all SIP enabled components, like Gateways, Call Manager, SIP Proxy Server and CVP SIP Subsystem . As shown in the image.
After the SIP signal flow is established the media path is negotiated and established. B2BUAs do not perform media termination of any kind, or sniff of Real Time Protocol (RTP) packets in a forward manner for inband rfc2833 Dual Tone Multy Frequency (DTMF) detection. The bearer path is established directly between the caller and called party endpoints. The media path does not hairpin through CVP.
Here you see the three basic, but most common SIP and CVP call flows.
Basic SIP Call Flow – No Proxy
Here is a SIP basic call flow with no SIP Proxy server deployed.
Basic SIP Call Flow – Proxy
Here is a SIP basic call flow with SIP Proxy server deployed.
CVP System Call Flow
The SIP proxy and Ingress gateway have been omitted for simplicity. Not all SIP messages are shown in the image.