A communication device and a method for circuit switched fallback (CSFB) configured to conduct inter radio access technology (RAT) measurements upon receipt of a CSFB notification and later use the information obtained from the measurements to intelligently conduct a cell selection procedure if redirection to the target RAT frequency indicated by the Evolved Universal Terrestrial Radio Access Network (EUTRAN) in a CSFB redirection request fails.

When a UE is served by a first RAN and engages in signaling via the first RAN with a second RAN for the second RAN serve the UE with a call (e.g., in a circuit-switched fallback process), the second RAN will determine a speed of movement of the UE and will decide based on the speed of movement whether to provide the UE with a second-RAN traffic channel assignment in addition to providing the UE with an indication of second-RAN coverage in which the call will be served. For instance, if the UE is moving at a threshold high rate of speed, then the entity will provide the UE with a second-RAN traffic channel assignment so as to help expedite the start of the call and to help avoid an issue where the UE may move out of the second-RAN coverage in which the call is to be served.

Methods and apparatuses are provided for handling Internet protocol (IP) multimedia subsystem (IMS) and circuit switch fall back (CSFB) calls at a user equipment (UE) in a wireless network. A non-access stratum (NAS) of the UE receives an IMS indication when an IMS call is initiated at the UE. The NAS determines a state of the UE. The NAS performs an action based on the state of the UE to trigger one of the IMS call and a CSFB call.

A method of supporting fast dual connectivity (DC) configuration after fallback in a 4G/5G network is proposed. A UE is configured with MR-DC (Multi-RAT Dual Connectivity) and is connected to both LTE/NR RAT in LTE/NR serving cells of master cell group (MCG) and secondary cell group (SCG). The UE has to fall back to legacy 2G/3G RAT and is forced to release the DC configuration. The UE records the serving cell information before fallback procedure and sends assistant information of the DC configuration to the network after fallback procedure. The assistant information comprises the stored serving cell information and optional additional measurement results for candidate SCG cells. The assistant information allows the network to resume the highspeed data transmission soon after the fallback procedure.

A mobile communication device and method including a wireless transceiver and a controller is provided. The wireless transceiver performs wireless transmission and reception to and from an advanced network and a legacy network. The controller receives a message from the advanced network via the wireless transceiver for redirecting the mobile communication device from the advanced network to the legacy network in response to a request for a call, searches for a suitable cell in the legacy network via the wireless transceiver in response to receiving the message, and camps on the suitable cell for making the call via the wireless transceiver regardless of the suitable cell being of a low priority and whether there is another suitable cell of a normal priority or not.

A method comprises receiving information for handover of a user equipment from a first connection to a second connection. The information for handover comprises information of a real-time text component of a call in progress in the first connection. The first connection comprises one of a packet switched connection and a circuit switched connection, and the second connection comprises the other of a packet switched connection and a circuit switched connection. The method further comprises using the information for handover to enable continuity of the real-time text component in the second connection.

Key processing times (such as call setup delay, call failure rate, call success rate, etc.) and other relevant metrics are measured in their respective networks (i.e., in LTE or 3G/2G networks) from raw signaling by various time-synchronized probes in real-time. Raw signaling data are collected from such probes in run-time, and various KPIs such as the end-to-end call setup times, success rates or causes of failure from call initiation in the LTE network to call completion in a 2G/3G network by correlating various raw signaling data collected by the probes in real-time.

The present invention discloses a voice resource saving method, including: an MME sends a notification message to an eNodeB, which is used to instruct the eNodeB not to hand over, for a non-voice service, a UE from a LTE network to a CS domain of a 2G or a 3G network. Or, when an MSC determines that the circuit domain service is a non-voice service, the MSC sends a bearer release message to a base station to instruct the base station to release the voice resource. According to the the present invention, during implementation of a non-voice service, a handover of UE from an LTE network to a CS domain of a 2G or 3G network may not be triggered, or a voice resource reserved in the CS domain of the 2G or 3G network is released.

A communication method and apparatus is provided for enhancing video telephony service quality by protecting against call setup failure or service quality degradation caused due to switching of the User Equipment (UE) to a network which does not fulfill the data rate required for video telephony in the video call setup process. The communication method of a terminal in a mobile communication system according to the present disclosure includes transmitting a video telephony call setup request message, receiving a switching command for Circuit Switched Fall Back (CSFB), and setting, if the switching command includes a target cell type set to the 2nd Generation (2G) cell and if a 3rd Generation (3G) cell to which the terminal can access exists, up the video telephony call by switching a connection to the 3G cell.

A method of managing voice calls in LTE/4G telephony for a mobile handset roaming outside of its home network in a network where voice calls use 3G technology, using a Global Location Register (GLR) which is designed to manage registrations without informing the home network. The method involves registering the mobile handset in 4G at the roaming network, obtaining and prestoring 3G information for the mobile handset from the home network while the mobile handset is registered in 4G, obtaining a voice call request for the mobile handset; and reregistering the mobile handset in 3G at the roaming network to use circuit switch fallback for the voice call, the reregistering comprising using the prestored 3G information so that the home network does not have to be contacted.