UE Core Network Capability indicates the ability of a UE to connect to and communicate with different core networks including,

• Core Network support, which indicates the ability to connect and communicate with different core networks (2G/3G, 4G, 5G).
• IMS (IP Multimedia Subsystem) Support.

This information is typically exchanged between the UE and the network during the registration and attachment processes.

This information is essential for the network to understand the device's functionalities and capabilities, enabling the network to provide the appropriate services for the UE.