Which SIP header is used by Cisco Unified Communication Manager to support the Redirected Number ID Service?
CUCM uses sip diversion header in INVITE message to carryout Redirected Number ID service.
References: http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/9_0_1/ccmsys/CUCM_BK_CD2F83FA_00_cucm-system-guide-90/ CUCM_BK_CD2F83FA_00_system-guide_chapter_0101000.html#CUCM_TP_R3F173A9_00
The SIP header used by Cisco Unified Communication Manager (CUCM) to support the Redirected Number ID Service is the Diversion header. The Diversion header is used to indicate that a call has been diverted or forwarded to a new destination. It contains information about the new destination, including the number that the call was forwarded to and the reason for the forwarding.
The Diversion header is added to the SIP message by the network element that forwards the call, such as a session border controller (SBC) or a SIP proxy server. When CUCM receives the SIP message with the Diversion header, it uses the information in the header to determine the correct display name and number to present to the called party.
The other SIP headers listed in the answer choices are as follows:
Replaces: This header is used to replace an existing SIP session with a new one. It is used when a call is transferred or when a user puts an active call on hold and retrieves it later.
RPID (Remote-Party-ID): This header is used to convey the identity of the remote party in a SIP session. It is typically used to display the name and number of the calling party to the called party.
Join: This header is used to add a participant to a conference call.
P-Charging-Vector: This header is used for charging purposes in a SIP session. It contains information about the charges incurred during the session, such as the rate per unit and the duration of the session.