A system for mobile communication includes: a plurality of UEs forming a group, a RAN (Radio Access Network), an SCS (Service Capability Server), a first node and a second node; wherein the SCS is used for sending a message including an external group ID to the first node, the first node verifies that the SCS is authorized to send the message, the first node sends an internal group ID to the second node, and the second node broadcasts group messages via the RAN to the multiple UEs located in a particular geographic area.