A mobile communication method according to the present invention includes the steps of: sending “INVITE” from a UE#1 to a P-CSCF/VATF in a visited network of the UE#1; sending “INVITE” from the P-CSCF/VATF to an IMS; and allocating, by the P-CSCF/VATF, an MGW#1 to the path for voice communications.

A User Equipment (UE) including a controller configured to perform, in a case of failure of a connection attempt for a first emergency call that uses a Packet Switched (PS) domain, a connection attempt for a second emergency call that uses the PS domain, a transmission and/or reception unit configured to receive a service reject message due to the failure of the connection attempt for the first emergency call, wherein the UE uses a first access network for the connection attempt for the first emergency call, and the UE uses a second access network for the connection attempt for the second emergency call. Accordingly, a user equipment, a core network apparatus, a control method to be performed by an IMS apparatus, and the like are provided for the user equipment to connect to a network suitable for an emergency call service in 5th generation (5G) mobile communication system, which is a next-generation mobile communication system.

Systems and methods are disclosed for a 3G gateway. In one embodiment, a system is disclosed, comprising a gateway situated between a 3G radio access network (RAN) and a core network, the gateway providing resource management for a nodeB, and providing routing and node management for another base station, wherein the base station may be configured to provide, as a virtual RNC, radio resource control, power control, ciphering, and multiplexing of multiple users onto a transmission path for a first mobile device attached to the nodeB; the gateway may be configured to relay traffic for a second mobile device attached to the base station; and the gateway may be configured to relay traffic to the core network from both the nodeB and the base station via an IuCS interface and an IuPS interface.

A User Equipment (UE) including a controller configured to perform, in a case of failure of a connection attempt for a first emergency call that uses a Packet Switched (PS) domain, a connection attempt for a second emergency call that uses the PS domain, a transmission and/or reception unit configured to receive a service reject message due to the failure of the connection attempt for the first emergency call, wherein the UE uses a first access network for the connection attempt for the first emergency call, and the UE uses a second access network for the connection attempt for the second emergency call. Accordingly, a user equipment, a core network apparatus, a control method to be performed by an IMS apparatus, and the like are provided for the user equipment to connect to a network suitable for an emergency call service in 5th generation (5G) mobile communication system, which is a next-generation mobile communication system.

In some examples, a device detects a calling identifier received as part of initiating a call matches an emergency identifier, the emergency identifier associated with information from which to derive a Uniform Resource Name (URN). The device detects that the device is attached to or registered a first network different from a second network, where the second network configured the emergency identifier. In response to detecting that the device is attached to or registered the first network different from the second network, the device includes a Session Initiation Protocol (SIP) Uniform Resource Identifier (URI) in a Session Initiation Protocol (SIP) INVITE message to be transmitted.

A method for topology hiding is disclosed, comprising: receiving, at a gateway, the gateway positioned between a core network and a radio access network, a configuration information request from a base station; analyzing, at the gateway, a topology of the radio access network, the radio access network including the base station; grouping, at the gateway, the base station into a first group based on the topology; sending, from the gateway to the base station, a grouping message to indicate that the base station be placed in the first group; and terminating connections from the core network to one or more base stations in the first group at the gateway as a back-to-back proxy, thereby hiding the topology of the radio access network from the core network.

Systems and methods are disclosed for a 3G gateway. In one embodiment, a system is disclosed, comprising a gateway situated between a 3G radio access network (RAN) and a core network, the gateway providing resource management for a nodeB, and providing routing and node management for another base station, wherein the base station may be configured to provide, as a virtual RNC, radio resource control, power control, ciphering, and multiplexing of multiple users onto a transmission path for a first mobile device attached to the nodeB; the gateway may be configured to relay traffic for a second mobile device attached to the base station; and the gateway may be configured to relay traffic to the core network from both the nodeB and the base station via an IuCS interface and an IuPS interface.

Reliable call hand-offs from a cellular network to a Wi-Fi network. A hand-off controller detects a hand-off condition (e.g., hand-off request, potential/predicted hand-off request) and, in response, initiates a test call. For example, a telephone call made through a smart phone, using a cellular network (e.g., Verizon, AT&T or Sprint) can be handed over to a hot spot at a Starbucks. In response to detecting an available data network, transmission quality for VOIP conditions is automatically tested. If the network conditions meet a certain predetermined threshold, the VOIP hand-off is executed. If the predetermined threshold is not met, the VOIP hand-off may not be executed, or may be delayed.

Systems and methods are disclosed for a 3G gateway. In one embodiment, a system is disclosed, comprising a gateway situated between a 3G radio access network (RAN) and a core network, the gateway providing resource management for a nodeB, and providing routing and node management for another base station, wherein the base station may be configured to provide, as a virtual RNC, radio resource control, power control, ciphering, and multiplexing of multiple users onto a transmission path for a first mobile device attached to the nodeB; the gateway may be configured to relay traffic for a second mobile device attached to the base station; and the gateway may be configured to relay traffic to the core network from both the nodeB and the base station via an IuCS interface and an IuPS interface.

A method of operating a user terminal in a telecommunications network. A telephony call is established between a first user, associated with the user terminal, and a remote user. Data communications is conducted between the user terminal and a communications server, such that the user terminal has a first connection to a communications session associated with a communications server. The telephony call is manipulated such that the telephony call forms a second connection to the communications session. Both the first connection and the second connection are maintained, for conducting communications between the first user and the remote user. The second connection may be terminated after assessment is made that the first connection is likely to provide better quality of service.