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.

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.

Enablement of a voice channel being established between an IoT device and a controller through the use of a voice-line service system.

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.