A method of packet domain event reporting performed by a user equipment (UE) including a mobile termination (MT) and a terminal equipment (TE), and the user equipment thereof. The method according to one embodiment includes performing, by the MT, context activation for establishing a dual-stack bearer between the MT and a network; receiving, by the MT from the network, information indicating that the context activation of the dual-stack bearer is not possible between the network and the MT; and sending, by the MT to the TE, a message including a reason parameter for indicating a reason as to why the context activation of the dual-stack bearer is not possible between the network and the MT, when a requested Packet Data Protocol (PDP) type is Internet Protocol (IP) v4v6 and a assigned PDP type is either IPv4 or IPv6.