• OverView
• Features

The Proxy-Call State control function is first contact point in an IMS network for the User Equipment. The Proxy-Call State Control Function can reside in Home Network (Service Provider Network) or Visited Network (Roaming Network). Proxy-Call State Control Function acts as a Proxy Server as defined in SIP RFC 3261. However, it supports some additional headers defined by 3GPP for IMS as SIP extensions, described in following section. In rare cases, the P-CSCF may behave as a User Agent .The latter behavior is used for abnormal cases where it is needed for independent transactions, generations and terminations.

Features

• PCRF
• SIP Compression
• PDF Client
• Registrar
• Offline Client
• Emergency Call Screening
• NAT Firewall Traversal
• IPSec

Interrogating-Call State Control Function is first contact point within an operator or service provider network for inbound calls from outside the network. I-CSCF is used for selecting appropriate S-CSCF function that will serve the user. It manages the registration, session related and session-unrelated message flows and charging data generation.

Features

• SCSCF Assignment
• HSS Client
• Offline Client
• Trusted Domain Verification

The Serving‑CSCF (S‑CSCF) performs the session control services for the UE. It maintains a session state as needed by the network operator for support of the services. In an operator network there may be different S-CSCFs with different functionalities. S-CSCF is core switch or brain of an IMS network, with Registration, Session Management, Routing logic and Charging and resource utilization functions embedded into it.

Features

• E.164 DNS Translation
• HSS Client
• Registrar and Authentication
• Online Client
• Offline Client
• Event Subscription and Notification
• Routing
• Initial Filter Criteria Processing and Caching