Patent attributes
A disclosure of the present specification provides a method for establishing a packer data network (PDN) connection by a user equipment (UE). The method may comprise the steps of: transmitting a session initiation protocol (SIP)-based request message for requesting sending of a voice over LTE (VoLTE) call through a first type PDN connection; receiving, from a network node, a message including information directly or indirectly indicating that there is a problem in the first type PDN connection, instead of a normal response message to the SIP-based request message; determining to change the PDN type from the first type to a second type, on the basis of the information in the received message; and transmitting, to a mobility management entity (MME), a PDN connection request message including information on the changed second type.
