Abstract: This disclosure describes a communication system associated with a radio access technology (RAT). The communication system includes an Internet protocol (IP) multimedia subsystem (IMS) server, and one or more processors configured to perform operations. The operations include receiving, from a user equipment device (UE) camped on the RAT, a request for IMS Packet Data Unit (PDU) establishment or IMS session initiation protocol (SIP) registration; sending to the UE a rejection message associated with the SIP registration or the IMS PDU establishment; receiving, from the UE, an IMS failure message that comprises an IMS failure cause; determining, based on the IMS failure message, whether the IMS failure cause is temporary or permanent; and responsive to determining that the IMS failure is temporary, temporarily disabling the RAT for the UE.

Abstract: This disclosure describes a user equipment device (UE). The UE includes one or more antennas; one or more radios configured to perform cellular communication using a plurality of radio access technologies (RATs) that support voice over an Internet protocol (IP) multimedia subsystem (IMS); and one or more processors coupled to the one or more radios. The one or more processors are configured to cause the UE to perform operations including: sending, to a communications network associated with a first RAT of the plurality of RATs, a first request for IMS registration, wherein the UE is camped on a first cell of the first RAT; determining, based on an IMS rejection failure, that the IMS registration failure is due to a temporary radio failure; and responsively attempting to perform the IMS registration on at least one other cell of the first RAT.

Abstract: This disclosure describes a communication system associated with a radio access technology (RAT). The communication system includes an Internet protocol (IP) multimedia subsystem (IMS) server, and one or more processors configured to perform operations. The operations include receiving, from a user equipment device (UE) camped on the RAT, a request for IMS Packet Data Unit (PDU) establishment or IMS session initiation protocol (SIP) registration; sending to the UE a rejection message associated with the SIP registration or the IMS PDU establishment; receiving, from the UE, an IMS failure message that comprises an IMS failure cause; determining, based on the IMS failure message, whether the IMS failure cause is temporary or permanent; and responsive to determining that the IMS failure is temporary, temporarily disabling the RAT for the UE.

Abstract: This disclosure describes a user equipment device (UE). The UE includes one or more antennas; one or more radios, where each of the radios is configured to perform cellular communication using a plurality of radio access technologies (RATs) that support voice over an Internet protocol (IP) multimedia subsystem (IMS); one or more processors coupled to the one or more radios, where the one or more processors are configured to cause the UE to perform operations including: sending, via a first RAT, a first request for IMS registration to an IMS server; receiving, from the IMS server, an IMS rejection message indicating failure of the IMS registration; determining, based on the IMS rejection message, that the IMS registration failure is temporary; responsively re-attempting IMS registration with the IMS server; and determining to camp on the first RAT in response to receiving an IMS acceptance message from the IMS server.

Abstract: The present application relates to devices and components including apparatus, systems, and methods to provide call collision resolution procedures in wireless communication systems.

Abstract: Techniques described herein may increase the efficiency of a network by ensuring that bearers, used in anonymous (e.g., emergency) calls are properly deactivated. A user equipment (“UE”) may maintain an inactivity timer after an emergency call has ended, and may request that the network deactivate the bearer upon expiration of the inactivity timer, if the bearer is still active upon the expiration of the inactivity timer.