Apple Inc.

Intel IP Corporation

Deepak Dash

Krisztian Kiss

Alexandre Saso Stojanovski

Robert Zaus

Karthik Anantharaman

Nitin Kuppelur

Anish George

Sridhar Prakasam

Nirlesh Koshta

Kavya B Ravikumar

Roland Gruber

Nitin Gowda Basavarajappa

Vijay Katakam

Anuroop Sobhan Madupu

Udaysinh Bhosale

Gowda Basavarajappa Nitin

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.

Voice over internet protocol multimedia subsystem

A user equipment (UE) transmits a registration request message to a first public land mobile network (PLMN), wherein the first PLMN is a roaming PLMN, receives a registration accept message from the first PLMN, determines that the registration accept message includes a manipulated steering of roaming (SoR) container or does not include a SoR container, wherein the SoR container is configured by a home PLMN (HPLMN) of the UE and transmitted to the first PLMN from the HPLMN, determines that the registration accept message includes an indication that the first PLMN does not support voice over packet switching (VoPS) and adds the first PLMN to a first list of PLMNs in which voice service is not possible in an N1 mode.

Handling PLMN prioritization

Systems and methods provide steering of roaming (SoR) information during a user equipment (UE) mobility registration process. In other systems and methods, instead of triggering mobility and periodic registration, a UE performs initial registration until a valid SoR is received in a visited country or network as long as a subscriber identification module (SIM) or a universal SIM (USIM) of the UE indicates that the UE is expected to receive SoR information due to initial registration in a visited public land mobile network (VPLMN).

Steering of roaming check during mobility registration

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.

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.

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Bengaluru, India

Deepak Dash