Voice over internet protocol multimedia subsystem

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.

We claim: 
     
         1 . A communication system associated with a radio access technology (RAT), the communication system comprising:
 an Internet protocol (IP) multimedia subsystem (IMS) server; and   one or more processors configured to perform operations comprising:
 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. 
   
     
     
         2 . The communication system of  claim 1 , wherein the IMS failure message further comprises an IMS retry timer. 
     
     
         3 . The communication system of  claim 2 , the operations further comprising:
 generating a RAT disable timer based on the IMS retry timer, wherein the communication system is configured to re-enable the temporarily disabled RAT upon expiration of the RAT disable timer.   
     
     
         4 . The communication system of  claim 3 , the operations further comprising:
 sending the RAT disable timer to the UE.   
     
     
         5 . The communication system of  claim 3 , the operations further comprising:
 detecting expiration of the RAT disable timer; and   responsively re-enabling the RAT for the UE.   
     
     
         6 . The communication system of  claim 1 , wherein determining that the IMS failure is temporary occurs in a first instance of performing the operations, and wherein in a second instance of performing the operations:
 determining that the IMS failure is permanent; and   responsively disabling the RAT for the UE permanently.   
     
     
         7 . The communication system of  claim 6 , wherein permanently disabling the RAT for the UE comprises permanently disabling the RAT until usage settings of the UE change or the UE's power cycles. 
     
     
         8 . The communication system of  claim 1 , wherein the RAT is a 5th generation mobile communication system (5GS) that supports voice over IMS. 
     
     
         9 . A user equipment device (UE), comprising:
 one or more antennas;   one or more radios configured to perform cellular communication using a radio access technology (RAT) that supports voice over an Internet protocol (IP) multimedia subsystem (IMS), wherein the UE is camped on the RAT;   one or more processors coupled to the one or more radios, wherein the one or more processors are configured to cause the UE to perform operations comprising:
 sending, to a communications network associated with the RAT, an IMS session initiation protocol (SIP) registration message; 
 receiving, from the communications network, a message indicative of SIP rejection; 
 determining, based on the message indicative of the SIP rejection, that the SIP rejection is temporary; 
 starting an IMS retry timer, wherein the UE is configured to reattempt SIP registration upon expiration of the IMS retry timer; and 
 sending to the communications network an IMS failure message that comprises at least one of an IMS failure cause or an IMS retry timer. 
   
     
     
         10 . The UE of  claim 9 , wherein the operations further comprise:
 determining a new value for the IMS retry timer, wherein the new value is synchronized with a RAT disable timer starting.   
     
     
         11 . The UE of  claim 10 , wherein determining a new value for the IMS retry timer comprises:
 receiving from the communications network the new value for the IMS retry timer.   
     
     
         12 . The UE of  claim 10 , wherein determining a new value for the IMS retry timer comprises:
 calculating the new value using predetermined values provided by the communications network.   
     
     
         13 . The UE of  claim 9 , the operations further comprising:
 detecting expiration of the IMS retry timer; and   responsively reattempting SIP registration with the communications network.   
     
     
         14 . The UE of  claim 9 , wherein the RAT is a 5th generation mobile communication system (5GS). 
     
     
         15 . A non-transitory computer readable memory medium storing program instructions executable by processing circuitry to cause a user equipment device (UE) to perform operations comprising:
 sending, to a communications network associated with a radio access technology (RAT) on which the UE is camped, an IMS session initiation protocol (SIP) registration message;   receiving, from the communications network, a message indicative of SIP rejection;   determining, based on the message indicative of the SIP rejection, that the SIP rejection is temporary;   starting an IMS retry timer, wherein the UE is configured to reattempt SIP registration upon expiration of the IMS retry timer; and   sending to the communications network an IMS failure message that comprises at least one of an IMS failure cause or an IMS retry timer.   
     
     
         16 . The non-transitory computer readable memory medium of  claim 15 , wherein the operations further comprise:
 determining a new value for the IMS retry timer, wherein the new value is synchronized with a RAT disable timer starting.   
     
     
         17 . The non-transitory computer readable memory medium of  claim 16 , wherein determining a new value for the IMS retry timer comprises:
 receiving from the communications network the new value for the IMS retry timer.   
     
     
         18 . The non-transitory computer readable memory medium of  claim 16 , wherein determining a new value for the IMS retry timer comprises:
 calculating the new value using predetermined values provided by the communications network.   
     
     
         19 . The non-transitory computer readable memory medium of  claim 15 , the operations further comprising:
 detecting expiration of the IMS retry timer; and   responsively reattempting SIP registration with the communications network.   
     
     
         20 . The non-transitory computer readable memory medium of  claim 15 , wherein the RAT is a 5 th  generation mobile communication system (5GS).