Reference Architecture of R00

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Reference Architecture of R00
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Support of Roaming Subscribers

• via the service platform in the Home Network
• via an external service platform

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UE Accessing IM Subsystem Services

• In the visited network

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Public and Private Identities

• One or more private user identities
• IMSI within a NAI
• is not used for routing of SIP messages
• One or more public user identities

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Relationship of Private and Public User
Identities
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Roles of CSCF

• Call State Control Function
• SIP proxy servers
• Proxy CSCF
• The first contact point within the IM subsystem
• Forward the SIP register requests from the UE to
  an I-CSCF
• Forward the SIP messages from the UE to the
  S-CSCF
• CDR
• Authorisation of bearer resources and QoS
  management. For details see TS 23.207

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• Interrogating CSCF
• The contact point within an operators network
• Assign an S-CSCF to a user performing SIP Reg
• Route a SIP request received from another network
  towards the S-CSCF
• Obtain from HSS the address of the S-CSCF
• Forward the SIP request or response to the S-CSCF
  determined by the step above
• CDR

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• Serving CSCF
• A registrar
• Session control for the registered endpoint's
  sessions.
• Interaction with Services Platforms
• On behalf of an originating endpoint
• On behalf of an destination endpoint
• CDR
• Authenticate the UEs

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Registration Information Flow
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Re-Registration
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Node Before Registration During Registration After Registration
UE - in local network Credentials Home Domain Proxy Name/Address Same as before registration Credentials Home Domain Proxy Name/Address
Proxy-CSCF - in Home or Visited network Routing Function Initial Network Entry point UE Address Public and Private User IDs Final Network Entry point UE Address Public and Private User IDs
Interrogating-CSCF - in Home network HSS or SLF Address Serving-CSCF address/name P-CSCF Network ID Home Network contact Information No State Information
HSS User Service Profile P-CSCF Network ID Serving-CSCF address/name\
Serving-CSCF (Home) No state information HSS Address/name User profile (limited as per network scenario) Proxy address/name P-CSCF Network ID Public/Private User ID UE IP Address May have session state Information Same as during registration
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De-registration
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Call flow
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Different Kinds of CSCFs
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PSTN origination procedure
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PSTN origination procedure
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PSTN termination procedure
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PSTN termination procedure