IMS

 

 

 

 

SIP Parameters : P-Called-Party-ID

 

This parameter is designed to compensate any possible uncertainty of destination address ("to" parameter). Since "to" parameter is populated by UA, not by Proxy it may have some missing details. To handle this situation, Proxy server can add P-Called-Pary-ID to clarify the destination address.

This parameter is most commonly used in INVITE, MESSAGE request.

 

Note 1: A UAC MUST NOT insert a P-Called-Party-ID header field in any SIP request or response. (RFC 3455, 4.2.2.1 Procedures at the UA)

 

Note 2: The proxy must know in adevance the information about the user, in order to prevent a wrong delivery of the called party ID. The proxy may got the information in previous procedure like Registration. (RFC 3455, 4.2.2.2 Procedures at the proxy)

 

Note 3: A SIP proxy MUST NOT insert a P-Called-Party-ID header in REGISTER requests(RFC 3455, 4.2.2.2 Procedures at the proxy)

 

See RFC 3455 with focus on following sections.

    4.2 The P-Called-Party-ID header : See Example here for clear understanding

    4.2.1 Applicability statement for the P-Called-Party-ID header

    4.2.2 Usage of the P-Called-Party-ID header

    4.2.2.1 Procedures at the UA

    4.2.2.2 Procedures at the proxy