If the resource allocation is initiated by the UE, the UE starts reserving resources whenever it has sufficient information about the media streams, and used codecs available as specified in TS 24.501 and TS 24.502.

If the UE is configured not to initiate resource allocation for media according to TS 24.167, then the UE shall refrain from requesting additional 5GS QoS flow(s) for media until the UE considers that the network did not initiate resource allocation for the media.

If the UE receives an activation request from the network for a 5GS QoS flow for media which is associated with the 5GS QoS flow used for signalling, the UE shall correlate the media 5GS QoS flow with a currently ongoing SIP session establishment or SIP session modification. If the UE receives a modification request from the network for a 5GS QoS flow that is used for one or more media streams in an ongoing SIP session, the UE shall:

1. modify the related PDU session context in accordance with the request received from the network.

When a data stream for media related to a session is released, if the 5GS QoS flow transporting the data stream is no longer needed and allocation of the 5GS QoS flow was requested by the UE, then the UE releases the 5GS QoS flow.

The procedures specified in Annex U.2.2.5.2 apply.

Not applicable.

Emergency session is supported over the WLAN access if the UE has failed or has not been able to use 3GPP access to set up an emergency session as described in TS 23.167 annex L. IMS emergency session is also supported for UEs with unavailable IMSI (i.e. a UE without USIM) or unauthenticated IMSI. Some jurisdictions allow emergency calls to be made when the UE does not contain an ISIM or USIM, or where the credentials are not accepted. The UE determines that the 5GCN supports emergency services via WLAN when the Emergency service support for non-3GPP (EMCN3) access indicator in the REGISTRATION ACCEPT message indicates emergency services are supported over non-3GPP access as defined in subclause 9.11.3.5 of TS 24.501. When the UE is registered over a WLAN access and detects an emergency call attempt, if the UE supports the emerg-non3gpp timer defined in Table 7.8.1 and has determined that 5GCN supports emergency services via WLAN the UE shall start the emerg-non3gpp timer when starting a domain selection searching for a 3GPP access usable to establish an emergency call. The UE shall stop the timer when a 3GPP access supporting emergency call is found. When the emerg-non3gpp timer expires the UE shall consider that it has failed to use 3GPP access to setup the emergency call and shall attempt to setup the emergency call over the available WLAN access. The UE may support being configured for the emerg-non3gpp timer using one or more of the following methods:

1. the Timer_Emerg_non3gpp leaf of the EFIMSConfigData file described in TS 31.102;
2. the Timer_Emerg_non3gpp leaf of the EFIMSConfigData file described in TS 31.103; and
3. the Timer_Emerg_non3gpp leaf of TS 24.167.

When the IM CN subsystem is selected as the domain for the emergency call attempt, the UE determines whether it is currently attached to its home operator's network (e.g. HPLMN) or not (e.g. VPLMN) after it has determined that the 5GCN supports emergency services via WLAN. To perform emergency registration, the UE shall request to establish an emergency PDU session as described in TS 24.501. The procedures for PDU session establishment and P-CSCF discovery, as described in subclause W.2.2.1 of this specification apply accordingly. If the ME is equipped with a UICC, in order to find out whether the UE is attached to the home PLMN or to the visited PLMN, the UE shall compare the MCC and MNC values derived from its IMSI with the MCC and MNC of the PLMN the UE is attached to. If the MCC and MNC of the PLMN the UE is attached to do not match with the MCC and MNC derived from the IMSI, then for the purposes of emergency calls in the IM CN subsystem the UE shall consider to be attached to a VPLMN. If the ME is not equipped with a UICC, the procedure to find d out whether the UE is attached to the home PLMN or to the visited PLMN for the purpose of emergency calls in the IM CN subsystem, is implementation specific. If the UE detected an emergency number, the UE subsequently uses a different PLMN than the PLMN from which the UE received the last Extended Local Emergency Number List, the dialled number is not stored in the ME, in the USIM and in the Local Emergency Number List, and:

• the REGISTRATION ACCEPT message received from the different PLMN contains the Extended Local Emergency Number List and the emergency number is present in the updated Extended Local Emergency Number List then the UE uses the updated Extended Local Emergency Number List when it performs the procedures in subclause W.2.2.6.1B; and
• the REGISTRATION ACCEPT message received from the different PLMN contains no Extended Local Emergency Number List or the emergency number is no longer present in the updated Extended Local Emergency Number List then the UE shall attempt UE procedures for SIP that relate to emergency using emergency service URN "urn:service:sos".

If the dialled number is equal to a local emergency number stored in the Extended Local Emergency Number List (as defined in TS 24.301), then the UE shall recognize such a number as for an emergency call and:

• if the dialled number is equal to an emergency number stored in the ME, or in the USIM, then the UE shall perform either procedures in the subclause W.2.2.6.1B or the procedures in subclause W.2.2.6.1A; and
• if the dialled number in not equal to an emergency number stored in the ME, or in the USIM, then the UE shall perform procedures in the subclause W.2.2.6.1B.

If the dialled number is not equal to a local emergency number stored in the Extended Local Emergency Number List (as defined in TS 24.301) and:

• if the dialled number is equal to an emergency number stored in the ME, in the USIM or in the Local Emergency Number List (as defined in TS 24.008), then the UE shall recognize such a number as for an emergency call and performs the procedures in subclause W.2.2.6.1A.

Once IPsec tunnel setup is completed, the UE shall follow the procedures described in subclause W.2.2.1 of this specification for establishment of IP-CAN bearer and P-CSCF discovery accordingly. Upon reception of a 380 (Alternative Service) response to an INVITE request as defined in subclause 5.1.2A.1.1 and subclause 5.1.3.1, if:

• the 380 (Alternate Service) response contains a Contact header field;
• the value of the Contact header field is a service URN; and
• the service URN has a top-level service type of "sos";

then the UE determines that "emergency service information is included" as described TS 23.167. Upon reception of a 380 (Alternative Service) response to an INVITE request as defined in subclause 5.1.3.1, if the 380 (Alternate Service) response does not contain a Contact header field with service URN that has a top-level service type of "sos", then the UE determines that "no emergency service information is included" as described TS 23.167. Upon reception of a 380 (Alternative Service) response to an INVITE request as defined in subclause 5.1.2A.1.1 and subclause 5.1.3.1, the UE shall proceed as follows:

1. if a 3GPP access network is available and the UE has not already attempted to use a 3GPP access network to set up an emergency session as described in TS 23.167 annex L, when the UE selects a domain in accordance with the conventions and rules specified in TS 22.101 and TS 23.167, the UE shall attempt to select a domain of the 3GPP access network, and:
   • if the CS domain is selected, the UE behaviour is defined in subclause 7.1.2 of TS 23.167 and in annex B; and
   • if the IM CN subsystem is selected, the UE shall apply the procedures in subclause 5.1.6 with the exception of selecting a domain for the emergency call attempt;
   In addition, when the UE determines that "it has not been able to use 3GPP access to set up an emergency session" in accordance with subclause L.1 of TS 23.167, the UE shall apply the procedures in subclause 5.1.6 using WLAN, with the exception of selecting a domain for the emergency call attempt; and
2. if a 3GPP access network is not available, then the UE shall apply the procedures in subclause 5.1.6 using WLAN, with the exception of selecting a domain for the emergency call attempt.

When the emergency registration expires, the UE should disconnect the emergency PDU session.

Annex U.2.2.6.1A applies.

Annex U.2.2.6.1B applies.

The UE shall not send an INVITE request with Request-URI set to "urn:service:sos.ecall.manual" or "urn:service:sos.ecall.automatic".

The UE may support the current location discovery during an emergency call specified in subclause 5.1.6.8.2, subclause 5.1.6.8.3, subclause 5.1.6.8.4, and subclause 5.1.6.12.