P-CSCF Functions

The Oracle Communications Unified Session Manager performs the following functions in the role of P-CSCF:

• Forwards SIP REGISTER messages and maintains a cached mapping of the user info and the UE's Address of Record (AoR), including the far-end NAT address in the case of hosted NAT traversal (HNT).
• Performs local emergency session handling—Local routing policy is used by the Oracle Communications Unified Session Manager to identify emergency sessions and provide unique routing (e.g. can route to a dedicated S-CSCF function for emergency session handling).
• Operates as a UA (B2BUA) for generating independent SIP transactions for security purposes and handling of abnormal conditions.
• Offers current session timers which are used to monitor for media faults and abandoned calls.
• Generation of CDRs—The Oracle Communications Unified Session Manager generates real-time accounting records via RADIUS.
• Authorization of bearer resources and QoS management—With integrated BGF capabilities, the Oracle Communications Unified Session Manager allocates bearer resources (NAPT flows) and applies QoS policies (including packet marking) based on local policies and/or policies acquired via interaction with the A-RACF (PDF).
• Interaction with the A-RACF (PDF) for session-based policy enforcement and admission control—The Oracle Communications Unified Session Manager PDF interface options include COPS and SOAP/XML.
• Traffic Policing—Traffic is policed at the session and media/transport layer. At the signaling layer, the Oracle Communications Unified Session Manager polices at a number of levels including:
  • Capacity—Total number of concurrent calls to/from each realm
  • Session set-up rate—Maximum rate of call attempts to/from each signaling element
  • Signaling message rate—Each endpoint’s signaling message rate is monitored and policed
  • Signaling bandwidth—each endpoint’s signaling bandwidth is policed individually