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3GPP2 IMS Supplementary Services: Flexible Alerting. Introduction to Service. 3GPP-3GPP2 Common IMS Workshop 24-25 January 2008 Puerto Vallarta, Mexico Tdoc CIMS-080012. Textual Description of Flexible Alerting.
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3GPP2 IMS Supplementary Services: Flexible Alerting Introduction to Service 3GPP-3GPP2 Common IMS Workshop 24-25 January 2008 Puerto Vallarta, Mexico Tdoc CIMS-080012
Textual Description of Flexible Alerting • Application Server-based group termination service in which all members of the FA group are alerted in parallel. • The group is alerted by the dialing of a group identifier (i.e., a E.164 number or a SIP URI). The group identifier is referenced as the “pilot identity”. • The “pilot identity” maps to a set of public user identities (PUI), where each PUI references a member of the group • The set of PUIs can map to ANY combination of devices • For example - group of three members – T-Mobile CS device belonging to subscriber A, Verizon IMS device belonging to subscriber A, PSTN phone belonging to subscriber B • Terminating to the pilot identity results in the AS initiating a dialog with each of the group members. • The first member to answer is awarded the call – all other call ‘legs’ are abandoned • This feature is not SIP forking in IMS! See contrast and comparison on the following two slides
SIP Forking in IMS – Information Flow • ‘Fan out’ occurs at S-CSCF • Per IETF RFC 3261, many alerting patterns are possible: all parallel, strict sequential, sequential alerting of groups 1. INVITE (PUI) 2a. INVITE (PUI) S-CSCF Device 1 (Subscriber-A) 2b. INVITE (PUI ) Device 2 (Subscriber-A) 2c. INVITE (PUI) Device 3 (Subscriber-A)
3GPP2 Flexible Alerting – Info Flow • ‘Fan out’ occurs at AS pointed to by the S-CSCF associated with the pilot identity 2. INVITE (PUI=Pilot) 3a. INVITE (PUI #1) S-CSCF For ‘Pilot’ # AS for FA Device 1 (Subscriber-A) 3b. INVITE (PUI # 2) Device 2 (Subscriber-B) 3c. INVITE (PUI # 3) Device 3 (Subscriber-C)