Patent Description:
The communication of information from the UE to the home network via the visited network may take different routes, travel through different network elements based on, for example, the type of relation between the home and the visited network, or based on the technology of the networks. For example, a fifth generation (<NUM>) core network has different network elements compared to an Evolved Packet Core (EPC) network. EPC is a framework that provides converged voice and data in a fourth generation (<NUM>) wireless network, such as a Long Term Evolution (LTE) network.

The IMS contains, for example, a P-CSCF. The EPC contains, for example, a Mobility Management Entity (MME). The <NUM> CN contains, for example, an access and mobility management function (AMF).

Networks may offer a Circuit Switched (CS) domain, where traditionally voice calls and emergency calls are handled, or a Packet Switched (PS) domain, offering PS services including access to the IMS are handled.

The PS domain supports emergency services via the IMS. A UE may support accessing one or both of the CS domain and PS domain. A UE supporting PS domain may also support IMS. <CIT> describes a User Equipment configured to support access, via a serving network referred to as local network including an IMS network accessed by a PS domain, without user authentication, to services referred to as Local Services, including non-emergency services. <CIT> describes a method of locating an emergency voice session anchoring node of a plurality of emergency voice session anchoring nodes in an Internet Protocol Multimedia Subsystem of a serving communication network for transferring an emergency voice session of a terminal from a packet switched source radio access network of the serving communication network to a target radio access network of the serving communication network associated with a circuit switched domain of the serving communication network.

Accordingly there is provided a method, a User Equipment, and a non-transitory machine-readable medium as detailed in the appended claims.

Table <NUM> below lists various acronyms and abbreviations.

Table <NUM> below summarizes various terms used.

Emergency services may be identified by emergency numbers. Emergency numbers can be tied to emergency service types. Examples of emergency service types include police, ambulance, fire brigade, marine guard, mountain rescue, or any other emergency service type.

Regulators have the authority to define emergency services. Typically, a regulator reserves a number and associates an emergency service description with the number. The reserved number is referred to as an emergency number. For certain emergency service descriptions, it is straightforward to associate the emergency service description with an emergency service type. For other emergency service descriptions, it is not straightforward to associate the emergency service description with an emergency service type.

Emergency service types can be expressed in a category, represented by a binary information element. One or more bits of the category may be set to '<NUM>' to indicate an emergency service type. Alternatively, emergency service types can be expressed using a URN. A URN can take the form "urn:service:sos[. optional-dot-separated-labels-follow]", e.g., "urn:service:sos. police" or "urn:service:sos.

The UE, when detecting that an emergency number is dialled that matches an emergency number for a country, includes the emergency service type in the call setup or session setup message.

The emergency service type is included regardless of whether the UE is in limited service mode or not. A UE in limited service mode may not access services the UE has subscribed to. A UE in limited service mode can typically only invoke emergency services.

A UE is in limited service mode when it is in the limited service state. Subsequently, the UE can become emergency attached with an EPC network or emergency registered with a 5GC network, attached for emergency bearer services or registered for emergency services.

In some examples, a UE registers or attaches with a network before the UE can use (subscribed) services. The UE sends and receives NAS messages when registering or attaching with the network. In 5GS, a NAS message to request registration may include a REGISTRATION request message. In EPS, a NAS message to request registration may include a ATTACH request message. In response to a registration request the UE may receive a registration accept message. In 5GS, a NAS message corresponding to a registration accept message may include a REGISTRATION ACCEPT message. In EPS, a NAS message corresponding to a registration accept message may include a ATTACH ACCEPT message.

The UE receives an emergency number and associated information from which the UE can derive a URN. The derived URN represents the emergency service type. The derived URN is included in a SIP INVITE message when using the IMS via the PS domain to initiate an emergency session.

Emergency number and associated information from which the UE can derive a URN are provisioned via the Extended (Local) Emergency Number List (EENL) information element (IE).

Emergency number and associated information from which the UE can derive a URN can be optionally provisioned via the (Local) Emergency Number List (ENL) IE.

The EENL IE can be included in a ATTACH ACCEPT message, a REGISTER ACCEPT message, a TRACKING AREA UPDATE ACCEPT message, registration accept message, attach accept message or tracking area update accept message.

The EENL as defined in 3GPP TS <NUM>, is reproduced below:.

The purpose of this information element is to encode one or more local emergency number(s) together with a sub-services field containing zero ore more sub-services of the associated emergency service URN. An emergency service URN is a service URN with top level service type of "sos" as specified in IETF Request for Comments (RFC) <NUM>.

EXAMPLE <NUM>: If the associated emergency service URN is "urn:service:sos. gas", there is only one sub-service provided in the sub-services field which is "gas".

EXAMPLE <NUM>: If the associated emergency service URN is "urn:service:sos", there is no sub-services provided in the sub-services field and the length of the sub-services field is "<NUM>".

NOTE: The associated emergency service URN can be a country-specific emergency service URN as defined in 3GPP TS <NUM>.

The Extended Emergency Number List information element is coded as shown below.

The Extended Emergency Number List IE is a type <NUM> information element with a minimum length of <NUM> octets and a maximum length of <NUM> octets.

NOTE <NUM>: The length shall contain the number of octets used to encode the number digits.

NOTE <NUM>: The number digit(s) in octet <NUM> precedes the digit(s) in octet <NUM> etc. The number digit, which would be entered first, is located in octet <NUM>, bits <NUM> to <NUM>. The contents of the number digits are coded as shown in Table <NUM>. <NUM> of 3GPP TS <NUM>.

NOTE <NUM>: If the emergency number contains an odd number of digits, bits <NUM> to <NUM> of the last octet of the respective emergency number shall be filled with an end mark coded as "<NUM>".

NOTE <NUM>: The length shall contain the number of octets used to encode the sub-services field.

NOTE <NUM>: The characters of the sub-services of the associated emergency service URN shall be coded in accordance to 3GPP TS <NUM> and the first character starts in octet j+<NUM>, l+<NUM> or n+<NUM>.

EXAMPLE <NUM>: If the associated emergency service URN is "urn:service:sos. municipal", the sub-services field contains "police. municipal" and the first character is "p".

The SIP protocol includes request messages and response messages. SIP messages (request or response) are structured to include one or more header fields, followed by a body. The body may include zero or more bodies. A non-limiting example of a body is an Extensible Markup Language (XML) document or a SIP message or a fragment of a SIP message. Bodies are typed: a SIP message contained in another SIP message's body is typed message/sip, a SIP message fragment contained in another SIP message's body is typed message/sipfrag.

It has been proposed to delete the EENL (received from a first PLMN) upon successful registration with a second PLMN in the same country. If the EENL is deleted (and no EENL is received from the second PLMN in the same country), the UE may no longer detect that a dialled number is an emergency number, if the emergency number was included in the deleted EENL.

It is assumed that after successful registration, the second PLMN can detect whether a call to a dialled number is to be treated as emergency number (by means of network detected emergency call procedures).

However, if the second PLMN does not perform network detected emergency call procedures, the call may not be detected as emergency even though it was configured by a first PLNM by means of an EENL.

Further issues exist when the UE is in a limited service mode or when the UE attempts the call via WLAN to a network node of a third PLMN (in a different country). In the case of WLAN, if a 3GPP access is available the emergency call should be made over 3GPP access. Not having the EENL list may mean the UE can no longer detect that a dialled number is an emergency number, and the UE may attempt the undetected emergency call over the WLAN of the third PLMN in the different country.

Each PLMN in a country may tie or may associate an emergency number to or with a different emergency service type. The concept of PLMN specific emergency service types or unregulated (emergency) service types causes the following issues:.

In general, this means that a PLMN B in the same country as PLMN A, may not accurately route a call or session including an emergency service type identifier (e.g. the identifier in the aforementioned URN format), if the URN is provisioned at the UE by PLMN A.

With an increase of the number of digit strings that can be matched to an emergency number at the UE, there may be an increase in pocket dialled emergency calls (emergency calls dialled while the UE is in a pocket, purse, or other container, or any emergency calls not intended to be made by a user of the UE). Regulators may grow concerned about the number of failed emergency calls due to involuntarily or erroneously initiated emergency call.

Sections <NUM> and <NUM> address the issues in section <NUM>. <FIG> show three example scenarios in which techniques or mechanisms according to some implementations may be employed.

<FIG> shows an exchange of messages between a UE <NUM> and network nodes according to Scenario <NUM>. <FIG> shows usage of (extended) local emergency numbers. The following refers to tasks shown in <FIG>.

Task 1a: The UE <NUM> attempts to register by sending an ATTACH message or REGISTER message with a network node <NUM> of a <NUM>st PLMN in country A.

Task 1b: The network node <NUM> accepts the registration attempt. The network node <NUM> sends at least one emergency number and associated information from which the UE <NUM> can derive a URN. The at least one emergency number and the associated information can be sent in a mobility management message. The UE <NUM> receives the mobility management message from the network node <NUM>. The mobility management message can include a registration accept message. The registration accept message can include an ATTACH ACCEPT message or REGISTER ACCEPT message. The mobility management message received by the UE <NUM> contains the information sent by the network node <NUM>.

Task 2a: The UE <NUM> attempts to register by sending an ATTACH message or REGISTER message to a network node <NUM> of a <NUM>nd PLMN in country A.

Task 2b: The network node <NUM> accepts the registration attempt. The UE <NUM> does not receive at least one emergency number and associated information from which to derive a URN.

Task <NUM>: The UE <NUM> continues to use at least the at least one emergency number received from the network node <NUM> of the <NUM>st PLMN to detect if a dialled number in country A is an emergency number.

Task 1a: The UE <NUM> attempts to register by sending an ATTACH message or REGISTER message with the network node <NUM> of the <NUM>st PLMN.

Task 1b: The network node <NUM> accepts the registration attempt. The network node <NUM> sends at least one emergency number and associated information from which the UE <NUM> can derive a URN. The at least one emergency number and associated information can be sent in a mobility management message. The UE <NUM> receives the mobility management message from the network node <NUM>. The mobility management message can include a registration accept message. The registration accept message can include an ATTACH ACCEPT message or REGISTER ACCEPT message. The mobility management message received by the UE <NUM> contains the information sent by the network node <NUM>.

Task 2a: The UE <NUM> may enter a limited service state or a limited service mode.

Task 2b: The UE <NUM> attempts to be registered for emergency services by sending, to the network node <NUM> of the <NUM>nd PLMN, a REGISTER message indicating emergency, or the UE <NUM> attempts to be attached for emergency bearer services by sending, to the network node <NUM> of the <NUM>nd PLMN, an ATTACH message indicating emergency.

Task 2c: The network node <NUM> accepts the registration attempt. The UE <NUM> does not receive at least one emergency number and associated information from which to derive a URN.

Task 1a: The UE <NUM> attempts to register by sending an ATTACH message or REGISTER message to the network node <NUM> of the <NUM>st PLMN.

Task 1b: The network node <NUM> accepts the registration attempt. The network node <NUM> sends at least one emergency number and associated information from which to derive a URN. The at least one emergency number and associated information can be sent in a mobility management message. The UE <NUM> receives the mobility management message from the network node <NUM>. The mobility management message can include a registration accept message. The registration accept message can include an ATTACH ACCEPT message or REGISTER ACCEPT message. The mobility management message received by the UE <NUM> contains the information sent by the network node <NUM>.

Task 2a: If the UE <NUM> did not enter a limited service state, the UE <NUM> may not indicate emergency in the ATTACH message or REGISTER message. The UE <NUM> attempts to register by sending an ATTACH message or REGISTER message to the network node <NUM> of the <NUM>nd PLMN (had the UE entered limited service state or limited service mode, the ATTACH message may have indicated emergency or the REGISTER message may have indicated emergency).

Task 3a: The UE <NUM> may optionally connect via WLAN to a network node <NUM> in a <NUM>rd PLMN in a different country B, e.g., the home PLMN in the home country.

Task 3b: The UE <NUM> continues to use at least the at least one emergency number received from the network node <NUM> of the <NUM>st PLMN to detect if a dialled number in country A is an emergency number.

To protect a first PLMN in the same country against receiving unknown URNs or URNs the first PLMN has not configured at the UE <NUM>, the UE <NUM> may ignore the association between an emergency number and the information from which to derive a URN. The UE <NUM> may receive a list including at least one emergency number and associated information from which to derive a URN. The list may be received from a network node that is part of a second PLMN in the same country.

The UE may determine that the first and second PLMNs are in the same country by checking if the mobile country code (MCC) portion of the PLMN code associated with the first PLMN is part of the set of MCC codes that also includes the MCC portion of the PLMN code associated with the second PLMN. For most countries, the size of the set of MCC codes is one, i.e., the UE can effectively check if the MCC portion of the PLMN code associated with the first PLMN is equal to the MCC portion of the PLMN code associated with the second PLMN.

Rather than clearing the list, the list is kept (i.e., not cleared or not deleted or not replaced with an empty list) at the UE <NUM>. The advantage is that the UE <NUM> continues to be able to detect emergency numbers valid in the country. Furthermore, when the network to which the UE <NUM> is currently attached to or currently registered with is the second PLMN from which the UE received the list, the UE <NUM> would be able to use the information from which to derive a URN when the UE <NUM> returns to that second PLMN (e.g., in case where the UE <NUM> is in the limited service mode or limited service state or in case the PLMN selected for emergency calls over WLAN in the second PLMN).

"Emergency number and associated information from which the UE can derive a URN" or "Emergency number and associated URN" are received at the UE in an EENL IE. Alternatively, "Emergency number and associated URN" can be derived from the EENL IE. "Emergency number and associated information from which the UE can derive a URN" or "Emergency number and associated URN" can be stored in the UE. "Emergency number and associated information from which the UE can derive a URN" or "Emergency number and associated URN" can be obtained from the USIM or UICC or other persistent storage.

<FIG> is a flow diagram of a process <NUM> that can be performed by the UE <NUM>, according to first embodiments. The UE <NUM> receives (at <NUM>) at least one emergency number and associated information from which the UE can derive a URN. In some examples, the associated information can include the URN itself. In other examples, the associated information can include other information that the UE <NUM> can use to derive the URN.

The UE <NUM> detects (at <NUM>) that a dialled number matches one of the at least one emergency number.

The UE <NUM> detects (at <NUM>) that a first PLMN is different from a second PLMN, where the at least one emergency number and associated information from which the UE can derive a URN was configured by the second PLMN.

The UE includes (at <NUM>) the URN "urn:service:sos" in a SIP INVITE message to be transmitted to a network node.

In some examples, the at least one emergency number and associated information from which the UE can derive a URN is received from one of a Universal Subscriber Identity Module (USIM) or the second PLMN.

In further examples, the at least one emergency number and associated information from which the UE can derive a URN is received from one of a persistent memory, a Universal Integrated Circuit Card (UICC), an application on a UICC, a USIM, an IMS SIM (ISIM), or the second PLMN.

In some examples, the URN being configured by the second PLMN includes receiving the URN from the second PLMN.

The at least one emergency number and associated information from which the UE can derive the URN is received in a first Extended Emergency Number List (EENL) Information Element (IE), the EENL IE.

In further examples, the at least one emergency number and associated information from which the UE can derive the URN is received from one of a persistent memory, a UICC, an application on a UICC, a USIM, or an ISIM.

In some examples, the EENL IE is received from a network node that is part of the second PLMN.

In further examples, the EENL IE is received from a network node that is part of a core network of the second PLMN.

In some examples, the SIP INVITE message further includes dialled digits that make up the calling identifier. The dialled digits can be included in a header field of the SIP INVITE message or the dialled digits can be included in the body of the SIP INVITE message or body fragment part of the body of the SIP INVITE message. If the dialled digits are included in the body or body fragment (a single body is included in the SIP message's body, whereas multiple bodies to be included are each included in a portion or fragment of the SIP message's body), the content of the body to include the dialled digits is typed. Examples of these types are "message/sip" or "message/sipfrag". Other examples may exist. A network node in the PLMN receiving the dialled digits may be able to derive a service type from the dialled digits.

In some examples, the first PLMN is to be used to request an emergency service identified by the emergency number.

In further examples, the UE <NUM> can use a WLAN for sending the SIP INVITE message.

In some examples, the "at least one emergency number and associated information from which the UE can derive a URN" are not cleared when no new " at least one emergency number and associated information from which the UE can derive a URN" is received, while in the same country. While mapping of emergency number to emergency service type may not be applicable to all PLMNs in the same country, the other PLMNs do not receive emergency service type that is not applicable at that other PLMN.

In additional examples, a device (e.g., the UE <NUM>) receives, from a first network, at least one emergency identifier and associated information from which the device is able to derive an indicator (e.g., URN) of an emergency service type. The device stores the at least one emergency identifier and associated information. The device detects that a calling identifier received as part of initiating a call matches an emergency identifier. The device detects that the device is in the first network. In response to the detecting, the device uses the stored associated information to derive the indicator. The device sends a call initiation indication containing the indicator.

In further examples, detecting that the device is in the first network includes detecting that the device is in the second network prior to detecting that the device is in the first network.

In other examples, a non-transitory machine-readable medium comprises instructions that upon execution cause a device to receive, from a first network, at least one emergency identifier and associated information from which the device is able to derive an indicator of an emergency service type; after the receiving, detect that the device is in a second network different from the first network; and keep the at least one emergency identifier and associated information received from the first network in response to detecting that the device is in a second network different from the first network.

In further examples, the keeping is further in response to detecting, by the device, that the second network did not provide any emergency identifier to the device.

In the first embodiments described in section <NUM>. <NUM>, the detecting that the first PLMN is different from the second PLMN includes detecting that the first PLMN's PLMN code is not equal to the second PLMN's PLMN code.

The UE <NUM> may be configured with further PLMNs that are considered equivalent. Each further PLMN is identified with a unique, corresponding PLMN code. Each further PLMN's PLMN code may have been configured by receiving the PLMN code in one of an ATTACH ACCEPT message or REGISTRATION ACCEPT message.

In further examples, the detecting that the first PLMN is different from the second PLMN (as described in section <NUM>. <NUM>) includes detecting that the first PLMN's PLMN code is not equal to a third PLMN's PLMN code, the third PLMN being an equivalent PLMN of the second PLMN.

In some examples, <FIG> shows a process <NUM> of the UE including (at <NUM> in <FIG>) the URN "urn:service:sos" in the SIP INVITE message according to the first embodiments. The process <NUM> includes deriving (at <NUM>) a URN from the associated information from which the UE can derive a URN.

The process <NUM> further includes matching (at <NUM>) the derived URN with one or more well-known URNs. If the derived URN matches at least one of the one or more well-known URNs, the process <NUM> includes (at <NUM>) the derived URN in the SIP INVITE message.

If the derived URN does not match at least one of the one or more well-known URNs, the process <NUM> includes (at <NUM>) the URN "urn:service:sos" in the SIP INVITE message.

Thus, the UE <NUM> includes ing the URN "urn:service:sos" in the SIP INVITE message if the derived URN does not match at least one of the one or more well-known URNs.

In further examples, the UE <NUM> including the URN "urn:service:sos" in the SIP INVITE message includes matching the URN with one of the one or more well-known URNs, and if the URN matches at least one of the one or more well-known URNs, including the URN in the SIP INVITE message.

In some examples, the one or more well-known URNs include but are not limited to: "urn:service:sos", "urn:service:sos. ambulance", "urn:service:sos. police", "urn:service:sos. fire", "urn:service:sos. marine", "urn:service:sos. mountain", and so forth.

In further examples, the one or more well-known URNs further or alternatively include "urn:service:sos. manual", "urn:service:sos. automatic", and so forth.

Section <NUM>. <NUM> above refers to implementations for including a URN "um:service:sos" in a SIP INVITE message based on comparison to well-known emergency service types. In further examples, <FIG> shows a process <NUM> of another technique of the UE <NUM> according to the first embodiments for including (at <NUM> in <FIG>) the URN "urn:service:sos" in the SIP INVITE message. The process <NUM> includes deriving (at <NUM>) a URN from the associated information from which the UE can derive a URN. The process <NUM> verifies (at <NUM>) if the URN matches first characteristics. If the URN matches first characteristics, the process <NUM> includes (at <NUM>) the URN in the SIP INVITE message.

The UE including the "urn:service:sos" includes verifying if the URN does not match first characteristics, and if the URN does not match first characteristics, including (at <NUM>) the "urn:service:sos" in the SIP INVITE message.

The first characteristics include "urn:service:sos", "urn:service:sos. ambulance", "urn:service:sos. police", "urn:service:sos. fire", "urn:service:sos. marine", "urn:service:sos. mountain", and so forth.

Matching the first characteristics includes matching the first characteristics of the URN with "urn:service:sos. country-specific".

<FIG> shows a process <NUM> performed by the UE <NUM> according to second embodiments of the present disclosure.

The UE <NUM> receives (at <NUM>) at least one emergency number and associated information from which the UE can derive a URN. The associated information can be the URN itself, or other information from which the UE can derive the URN.

The UE <NUM> maintains (at <NUM>) a second PLMN code, where the at least one emergency number and associated information from which the UE can derive a URN was configured by the second PLMN and the second PLMN code identifies the second PLMN.

The UE <NUM> detects (at <NUM>) that a dialled number matches one of the at least one emergency number. The UE <NUM> detects (at <NUM>) a first PLMN code, where the first PLMN code identifies a first PLMN that is the same as the second PLMN.

The UE <NUM> derives (at <NUM>) a URN and includes (at <NUM>) the URN in a SIP INVITE message to be transmitted to a network node of the first PLMN.

In some examples, the at least one emergency number and associated information from which the UE can derive a URN is received in a first Extended Emergency Number List (EENL) Information Element (IE), the EENL IE.

In further examples, the at least one emergency number and associated information from which the UE can derive a URN is received from one of a persistent memory, a UICC, an application on a UICC, a USIM, or an ISIM.

In some examples, the detecting that the first PLMN is the same as the second PLMN includes detecting that the first PLMN code is not equal to the second PLMN code.

The UE <NUM> may be configured with further PLMNs that are considered equivalent. Each further PLMN is identified with a unique, corresponding PLMN code. Each further PLMN's PLMN code may have been configured by the UE receiving the PLMN code in one of an ATTACH ACCEPT message or REGISTRATION ACCEPT message.

In some examples, the detecting that the first PLMN is the same as the second PLMN includes detecting that the first PLMN code is equal to a third PLMN code identifying an equivalent PLMN of the second PLMN.

To protect a <NUM>st PLMN in a first country against call requests including emergency numbers valid in a second country, the UE <NUM> keeps emergency numbers the UE <NUM> has received while it is in the second country. The UE <NUM> may register with the <NUM>st PLMN in the first country via a non-3GPP access network such as a WLAN.

In the examples of sections <NUM>. <NUM> to <NUM>. <NUM> according to the first and second embodiments, the third PLMN may not be known at the UE <NUM>. The third PLMN is used for a call to an emergency number via a WLAN. Only an identifier used to identify a network element may be known. The network element can be identified by a "Emergency NAI (Network Access Identifier) for Limited Service State" or "IMSI (International Mobile Subscriber Identifier)-based Emergency NAI" or "ePDG (Evolved Packet Data Gateway) FQDN (Fully Qualified Domain Name) for emergency bearer services" or other identifier. Unless the PLMN that is connected via the network element is known, the techniques discussed in sections <NUM>. <NUM> to <NUM>. <NUM> are used. If the PLMN is not known, it is assumed that the PLMN is different from the second PLMN, and the techniques discussed in sections <NUM>. <NUM> to <NUM>. <NUM> are used.

To prevent the first PLMN in the same country from receiving an unknown URN, the UE <NUM> may alter the association between an emergency number and the information from which to derive a URN.

Rather than clearing the list, the list is kept at the UE <NUM>. The advantage may be that the UE <NUM> continues to detect emergency numbers valid in the country.

<FIG> is a flow diagram of a process <NUM> according to third embodiments. The UE receives (at <NUM>) at least one emergency number and associated information from which the UE can derive a URN. The UE detects (at <NUM>) that a first PLMN, where the first PLMN is to be used to request an emergency service identified by the emergency number, is different from a second PLMN, wherein the at least one emergency number and associated information from which the UE can derive a URN was configured by the second PLMN. The UE <NUM> changes (at <NUM>) the associated information from which the UE can derive a URN for the at least one of the at least one emergency number.

In some examples, the at least one emergency number and associated information from which the UE <NUM> can derive a URN is received in a in a first Extended Emergency Number List (EENL) Information Element (IE), the EENL IE.

In further examples, the at least one emergency number and associated information from which the UE <NUM> can derive a URN is received from one of a persistent memory, a UICC, an application on a UICC, a USIM, or an ISIM.

In a variant of the third embodiments, the first EENL IE includes a first field representing the length of a sub-services field and the corresponding sub-services field, associated with the at least one emergency number, wherein sub-services field is used to derive the URN. Also, changing the associated information for at least one of the at least one emergency number comprises creating a second EENL IE including at least one of the at least one emergency number and an associated second field representing the length of a sub-services field, wherein the length of the sub-services field is set to the value zero.

If the length of the sub-services field is the value zero, the UE <NUM> derives the URN "urn:service:sos" when dialled digits match the emergency number associated with the "length of the sub-services" field set to the value zero.

Techniques according to this section address issues described in section <NUM>.

In some countries it may not be desirable to enable a UE to recognize or detect all emergency numbers as eligible for limited service mode emergency calls.

However, making the detection dependent on whether the number is in EENL or ENL may not be correct because some countries include numbers suitable for inclusion in ENL only in the EENL.

In some examples, techniques can add to an EENL IE an indication of whether a number can be used for emergency call detection while the UE <NUM> is emergency attached with a core network.

Alternatively, techniques can add to an EENL IE an indication of whether information associated with a number can be used for deriving a URN, and a derived URN can be included in a SIP INVITE when the UE <NUM> is emergency attached with a core network.

Alternatively, techniques can add to an EENL IE an indication of whether the UE <NUM> is permitted to send a SIP INVITE with URN derived from the EENL while the UE <NUM> is emergency attached with a core network, if a number matches an emergency number in the EENL.

In some examples, the UE emergency being attached with a core network includes the UE is emergency being registered with a core network.

In further examples, the UE is emergency being attached with a core network includes the UE considering itself emergency attached with the core network.

The various alternative techniques described in this section can be combined.

The indication (or indicator or bit) as discussed in section <NUM>. <NUM> can be encoded in the Extended Emergency Number List IE as one or more of the bits of the field "Length of nth Emergency Number information". For example, the indication can be one of the bits <NUM>, <NUM>, <NUM>, or <NUM>, as follows:
<IMG>.

In further examples, the indication (or indicator or bit) as discussed in section <NUM>. <NUM> can be encoded in a different IE as one or more of the bits of the field associated with number digits:
<IMG>.

The following described further details according to various implementations of the present disclosure. The UE <NUM> can receive at least one emergency number and associated information from which the UE can derive a URN and an indication. The UE <NUM> detects that a dialled number matches one of the one or more emergency numbers. The UE <NUM> detects, prior to sending one or more SIP request messages, whether the UE is emergency registered.

If the UE <NUM> detects the UE is emergency registered and depending on the indication, the UE <NUM> refrains from sending at least one of the one or more SIP request messages. Alternatively, if the UE detects the UE is not emergency registered and depending on the indication, the UE sends the one or more SIP request messages.

The at least one emergency number and associated information from which the UE can derive a URN is received in a in a first Extended Emergency Number List (EENL) Information Element (IE), the EENL IE.

In the examples above, the at least one emergency number and associated information from which the UE can derive a URN is received from one of a persistent memory, a UICC, an application on a UICC, a USIM, or an ISIM.

In the examples above, the EENL IE is received from a network node part of a first PLMN.

In the examples above, the EENL IE is received from a network node part of a core network of a first PLMN.

In further examples, the UE <NUM> is emergency registered if at least one of the following is satisfied:.

In additional examples, the UE <NUM> detects whether the UE is emergency registered by at least one of:.

In further examples, the UE <NUM> detects the UE is not emergency registered by at least one of:.

In additional examples, the UE <NUM> can perform any or some combination of:.

Detailed changes are proposed below. Underlined, italic text indicates new text for current standards to realize part of the embodiments indicated in the subsection's title.

Modifications to the 3GPP TS <NUM> Specification are provided below, for implementing embodiments of section <NUM>.

In first embodiments in section <NUM>. <NUM>, the UE <NUM> including the "urn:service:sos" includes:.

The embodiments in this section clarified as follows, the first characteristics comprising "urn:service:sos", "urn:service:sos. ambulance", "urn:service:sos. police", "urn:service:sos. fire", "urn:service:sos. marine", "urn:service: sos.

A portion of modified 3GPP TS <NUM> is set forth below.

The Extended Local Emergency Number List (defined in 3GPP TS <NUM>) can contain sub-services of the associated emergency service URN for the detected emergency number.

If the network currently attached to is not the PLMN (or an equivalent PLMN of the PLMN) from which the Extended Local Emergency Number List was received, then the UE shall use the emergency service URN "urn:services:sos", unless the constructed URN matches e.g. "urn:service:sos. ambulance", "urn:service:sos. police", "urn:service:sos. fire", "urn:service:sos. marine", or "urn:service:sos.

A portion of modified modified 3GPP TS <NUM> for implementing embodiments of section <NUM> is set forth below.

If no Local Emergency Numbers List is contained in the ATTACH ACCEPT, REGISTER ACCEPT or in the TRACKING AREA UPDATE ACCEPT message, then the stored, first Local Emergency Numbers List in the user equipment shall be kept, except if the user equipment has successfully registered to a PLMN in a country different from that of the PLMN that sent the list. If no Extended Local Emergency Numbers List is contained in the ATTACH ACCEPT, REGISTER ACCEPT or in the TRACKING AREA UPDATE ACCEPT message, then the first Extended Local Emergency Numbers List or second Extended Local Emergency Numbers List in the user equipment shall be kept, with the following clarification, if:.

A portion of modified 3GPP TS <NUM> is provided below to implement the following tasks of section <NUM>.

The portion of modified 3GPP TS <NUM> is provided below:.

Various tasks discussed herein can be performed by a hardware processing circuit or a combination of a hardware processing circuit and machine-readable instructions executable on the hardware processing circuit. The hardware processing circuit can be part of a device such as a UE, a network node, and so forth. A hardware processing circuit can include a processor, such as any or some combination of a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, or another hardware processing circuit.

Machine-readable instructions executable on a processor can refer to the instructions executable on a single processor or the instructions executable on multiple processors.

A processor performing a task can refer to a single processor performing the task or multiple processors performing the task.

Machine-readable instructions can be stored in non-transitory machine-readable or computer-readable storage medium, which can include any or some combination of the following: a semiconductor memory device such as a dynamic or static random access memory (a DRAM or SRAM), an erasable and programmable read-only memory (EPROM), an electrically erasable and programmable read-only memory (EEPROM) and flash memory; a magnetic disk such as a fixed, floppy and removable disk; another magnetic medium including tape; an optical medium such as a compact disk (CD) or a digital video disk (DVD); or another type of storage device. Note that the instructions discussed above can be provided on one computer-readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine-readable storage medium or media is (are) considered to be part of an article (or article of manufacture). The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site (e.g., a cloud) from which machine-readable instructions can be downloaded over a network for execution.

Claim 1:
A method (<NUM>) of a user equipment, UE, (<NUM>), comprising:
receiving (<NUM>), at the UE, an Extended Local Emergency Number List, EENL, from a first Public Land Mobile Network, PLMN (<NUM>), the EENL provisioning at least one emergency number and associated information from which the UE can derive a Uniform Resource Name, URN;
detecting (<NUM>), by the UE, a dialled emergency number;
deriving (<NUM>, <NUM>), by the UE, a URN from the Extended Local Emergency Number List, the URN associated with the dialled emergency number;
detecting (<NUM>), at the UE, that the UE is attached to or registered with a second PLMN (<NUM>) different from the first PLMN; and
in response to the detecting that the UE is attached to or registered with the second PLMN different from the first PLMN,
verifying (<NUM>) whether the URN derived from the Extended Local Emergency Number List matches first characteristics, wherein the first characteristics includes one of "urn:service:sos", "um:service:sos.ambulance", "urn:service:sos.police", "urn:service:sos.fire", "urn:service:sos.marine", "urn:service:sos.mountain", and country-specific "urn:service:sos"; and
if the URN matches the first characteristics, including (<NUM>), by the UE, the URN in a Session Initiation Protocol, SIP, INVITE message to be transmitted by the UE, wherein the transmission of the SIP INVITE message is an attempt to initiate an emergency session.