Mapping of Diversion Information Between Diversion and History-Info Headers
History-Info and Diversion are the two headers in SIP signaling used to convey information related to call transfer and call diversion. Although both provide call diversion information, they have different syntaxes, the main difference being that the chronology of events is reversed between the two headers. To date, Oracle Communications Session Border Controllers have provided mapping and interworking of the History-Info and Diversion headers through the use of an SPL plug-in. This feature implements this interworking functionality within the software by adding a new parameter to the sip-interface configuration element.
The History-Info header is the standard solution adopted by the Internet Engineering Task Force (IETF) for storing retargeting information. The non-standard Diversion header also is used in many existing network implementations. As both headers provide call forwarding needs but have different syntaxes, having both present in a signaling request can cause diverting information to be misinterpreted unless an interworking solution exists. The solution currently is the use of a Session Plug-in Language (SPL) plug-in; however, this feature embeds the functionality within the software by adding the new parameter diversion-info-mapping-mode to the sip-interface configuration element. This functionality enables the SBC to construct a new History-Info header for each Diversion header or a new Diversion header for each History-Info header, initialized with the value of the History-Info header, when the SBC receives a SIP INVITE which does not contain a to-tag in the To header.
