HANDOVER SOURCE RADIO BASE STATION, HANDOVER DESTINATION RADIO BASE STATION, RADIO COMMUNICATION SYSTEM, AND RADIO COMMUNICATION METHOD

摘要

PROBLEM TO BE SOLVED: To surely perform handover of a VoLTE emergency call, when the handover with respect to the emergency call must be executed before a voice default bearer for the emergency call is established after a voice default bearer for a general call is established.SOLUTION: A radio base station determines whether or not a VoLTE call originated from a user device is an emergency call, on the basis of a message from the user device in originating the call. The radio base station comprises a handover request transmission unit for transmitting a handover request to another radio base station. The handover request transmission unit inserts information showing that the call is an emergency call into the handover request, in the case where it has been determined that the call is an emergency call when transmitting the handover request before a voice default bearer for the emergency call is established after a voice default bearer for a general call is established.