A method, an apparatus and a system for a handover to a circuit switched domain are disclosed. In an embodiment, a system includes a mobility management entity (MME) and at least two a mobile switching center (MSCs), wherein the at least two MSCs comprise a first MSC capable of supporting a circuit switched fallback (CSFB) and a single radio voice call continuity (SRVCC) and a second MSC not capable of supporting the SRVCC, and wherein the MME is configured to select the first MSC for a user equipment (UE) from the at least two MSCs in a combined tracking area update procedure of the UE when a location service of a circuit switched (CS) domain triggers an SRVCC procedure for the UE and when the UE has a Voice over Internet Protocol (VOIP) service in progress.

Embodiments of the present invention provide a method, apparatus, and system for a handover to a circuit switched domain. The method includes: selecting an MSC capable of both CSFB and SRVCC for a UE; and selecting, if a location service of a CS domain triggers an SRVCC procedure for the UE when the UE has a VOIP service in progress, the MSC capable of both CSFB and SRVCC in the SRVCC procedure, so that the UE, after being handed over to the CS domain, accesses the MSC and implements the location service of the CS domain. The apparatus includes: a first selecting module and a second selecting module. The system includes a UE and the apparatus. The embodiments of the present invention enable the UE with the VOIP service in progress to be correctly handed over to the CS domain and implement the location service.

An embodiment of the present invention makes it possible to appropriately identify a visitor and respond in a manner considered appropriate by a resident. A server includes: a face recognition section configured to carry out face recognition of a visitor who has inputted a call operation, based on a captured image obtained from an intercom slave unit; and an output control section which carries out control so that output is carried out, in accordance with the result of the face recognition, by at least one of the shared call unit, an indoor monitor, and a mobile terminal.

Technology for transcoding avoidance is disclosed. A mobile switching center (MSC) server can decode a single radio voice call continuity (SRVCC) packet switch (PS) to circuit switched (CS) request message received from a mobility management entity (MME) that includes selected CODEC information for a selected CODEC used for a user equipment (UE) in an internet protocol (IP) Multimedia Subsystem (IMS) over long term evolution (LTE) system. The MSC server can encode the selected CODEC information for transmission to a target MSC to enable the target MSC to identify the selected CODEC for the UE to allow the selected CODEC to be used in the CS domain.

Technology for transcoding avoidance during a single radio voice call continuity (SRVCC) procedure is disclosed. In an example, a mobile switching center (MSC) can include circuitry configured to: receive from a mobility management entity (MME) in a SRVCC packet switch (PS) to circuit switched (CS) request message, selected CODEC information for a selected CODEC used for a user equipment (UE) in an internet protocol (IP) Multimedia Subsystem (IMS) over long term evolution (LTE) system; and communicate the selected CODEC information to a target MSC to enable the target MSC to identify the selected CODEC for the UE to allow the selected CODEC to be used in the CS domain.

Techniques for call intent notification for establishing a call are described. According to one or more implementations, a user of a first user terminal attempts to establish a call with a second user terminal. Based on determining that the second user terminal and/or a user of the second user terminal is not available to answer the call, a call intent notification is sent to the second user terminal. According to one or more implementations, the call intent notification includes a number that enables the second user terminal to establish a call with the first user terminal.

Methods and systems for connecting isolated networks. One method includes storing, in a database of a network core, information related to a first set of communication devices associated with a first radio access network and a second set of communication devices associated with a second radio access network. The method further includes communicating between the network core and a transceiver of the first radio access network via an interface. The method further includes communicating, via the interface, between the network core and a virtual transceiver that represents an actual transceiver of the second radio access network.

When a first user intends a call with a second user via a packet switched communication service (e.g. VoIP), but the second user terminal or second user is currently unavailable to answer a call through the packet-switched service, then a call intent notification is sent to the second user terminal via an out-of-band communication channel, the call-intent notification notifying the second user about the intended call. Includes in the notification is a gateway PSTN number enabling the second user terminal to establish a hybrid PSTN call with the first user terminal via a connection between the second user terminal and a gateway over a PSTN network, and via a connection between the gateway and the first user terminal over the packet-switched network using the packet-switched communication service.

Embodiments of the present invention provide a method, apparatus, and system for a handover to a circuit switched domain. The method includes: selecting an MSC capable of both CSFB and SRVCC for a UE; and selecting, if a location service of a CS domain triggers an SRVCC procedure for the UE when the UE has a VOIP service in progress, the MSC capable of both CSFB and SRVCC in the SRVCC procedure, so that the UE, after being handed over to the CS domain, accesses the MSC and implements the location service of the CS domain. The apparatus includes: a first selecting module and a second selecting module. The system includes a UE and the apparatus. The embodiments of the present invention enable the UE with the VOIP service in progress to be correctly handed over to the CS domain and implement the location service.

Methods and systems for connecting isolated networks. One method includes storing, in a database of a network core, information related to a first set of communication devices associated with a first radio access network and a second set of communication devices associated with a second radio access network. The method further includes communicating between the network core and a transceiver of the first radio access network via an interface. The method further includes communicating, via the interface, between the network core and a virtual transceiver that represents an actual transceiver of the second radio access network.