A Proxy-CSCF (P-CSCF) is a SIP proxy that is the first point of contact for the IMS terminal. Assigned to an IMS terminal during the registration, and does not change during the duration of the registration.
- Authenticates the user and establishes IPsec security integration with the IMS terminal. Other nodes trust the P-CSCF, and do not have to authenticate the user again.
- Includes a Policy Decision Function (PDF), which authorizes media plane resources like QoS over the media plane. It is used for policy control, bandwidth management, etc.
- Generates charging records
OSIMS PCSCF component is based on Open IMS Core.