BGCF stands for Breakout Gateway Control Function, and it is a network element used in the IMS architecture to provide breakout functionality, which allows communication between different networks, such as a packet-switched (PS) network and a circuit-switched (CS) network. The BGCF is located at the edge of the IMS network, and it connects the PS domain and the CS domain.
The main functions of the BGCF in the IMS network are:
- Call routing: The BGCF routes calls between different networks, ensuring that the call is correctly handled by the destination network. The BGCF receives the request from the S-CSCF and determines the appropriate network to route the call to. The BGCF also provides the necessary signaling to establish and maintain the call.
- Number portability: The BGCF supports number portability, which allows users to keep their phone number when switching between networks. The BGCF queries the ENUM server or the NP server to find out the current network of the called party, and then routes the call accordingly.
- QoS management: The BGCF ensures that calls are delivered with the appropriate level of Quality of Service (QoS), based on the user’s requirements and the network’s capabilities. The BGCF negotiates the QoS parameters with the MGCF and the destination network, and allocates the necessary resources for the call.
- Security: The BGCF provides security features such as encryption and authentication to protect user data and prevent unauthorized access. The BGCF also enforces the network policies and regulations.
- Charging: The BGCF provides charging information to the charging system, which enables the network operator to bill the user correctly. The BGCF generates charging records for the calls that are routed through it, and sends them to the CDF.