Handling of Div Passport Headers for STIR

The handling of History-Info, Diversion, and Identity headers by the SBC is enhanced, as described below:

• If History-Info and Diversion headers are present in the ingress INVITE to the PSX, and you have configured the STI Profile in the Trunk Group, the SBC sends a maximum of five History-Info headers and five Diversion headers to the egress INVITE.

• The SBC filters out the History-Info headers added by network elements. It identifies such headers by the absence of the "user-info" part. For example, the SBC ignores "History-Info: <sip:proxy1.example.com>;index=1".

• The SBC ignores duplicate headers and History-Info headers that are same as the R-URI
• The SBC sends History-Info and Diversion headers to the PSX in the chronological order.
• The SBC sorts the History-Info headers by index, and sends the last five sorted History-Info headers.
• The SBC sorts the Diversion headers in the reverse order. If more than five Diversion headers are present in the INVITE, the SBC sends the last five Diversion headers after the reverse sort.

• If Identity headers are present in the ingress INVITE to the PSX, the SBC sends a maximum of ten Identity headers to the PSX. The order of preference is as follows:
  Table 1: Request - Preference for Header Inclusion
  

  Preference	Headers	Maximum Count
  1	Shaken identity header, if present in the ingress INVITE	1
  2	Rest of the Identity headers from the ingress INVITE, if present	9

• For response, the order of preference for the inclusion of the headers are as follows:
  
  Table 2: Response - Preference for Header Inclusion

  Preference	Headers	Maximum Count
  1	Shaken identity header (if present in the ingress INVITE), or an STI signed header	1
  2	Newly signed DIV identity headers	5
  3	Rest of the Identity headers from the ingress INVITE, if present	4