Capability Negotiation

SDP capability negotiation is the first phase of enabling DTMF transfer. The completion of the SDP offer/answer exchange yields a set of supported codecs between each UA and the Oracle® Enterprise Session Border Controller .

For DTMF transfer consideration, SDP manipulation is directed by parameters set in one of three configuration elements:

• codec policy
• signaling interface’s RFC 2833 mode
• session agent’s RFC 2833 mode

The Oracle® Enterprise Session Border Controller performs SDP manipulation (addition, removal, or modification of supported codecs) toward the called party first by any applicable codec policies. If one or more of the actions which define telephone-event Modification by Codec Policy occurs, then SDP manipulation is only performed by the codec policy configuration, not by RFC 2833 mode parameters in the signaling interface or session agent.

If a codec policy attached to either the ingress or egress realm triggers SDP manipulation, then the other realm uses codec policy for any telephone-event SDP manipulation; none of the RFC 2833 Mode configurations are used for SDP manipulation.

Note:

If the call does not trigger the evaluation of any codec policies, all DTMF transfer processing is only subject to RFC 2833 Mode rules.

If none of the telephone-event Modification by Codec occur, then the Oracle® Enterprise Session Border Controller performs SDP manipulation according to the RFC 2833 Mode parameters in the signaling interface or session agent.