(19)
(11)EP 3 278 585 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
11.12.2019 Bulletin 2019/50

(21)Application number: 15714213.4

(22)Date of filing:  01.04.2015
(51)International Patent Classification (IPC): 
H04W 4/90(2018.01)
H04W 60/00(2009.01)
H04W 8/20(2009.01)
H04W 92/02(2009.01)
H04M 3/51(2006.01)
H04L 29/06(2006.01)
H04W 76/50(2018.01)
H04W 80/10(2009.01)
H04W 12/06(2009.01)
(86)International application number:
PCT/EP2015/057265
(87)International publication number:
WO 2016/155827 (06.10.2016 Gazette  2016/40)

(54)

IMS EMERGENCY CALLS FOR ROAMING UES

IMS-NOTRUFE FÜR UMHERSCHWEIFENDE BENUTZERGERÄTE

APPELS D'URGENCE IMS POUR ÉQUIPEMENTS UTILISATEURS (UE) ITINÉRANTS


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
07.02.2018 Bulletin 2018/06

(60)Divisional application:
19206888.0

(73)Proprietor: Telefonaktiebolaget LM Ericsson (publ)
164 83 Stockholm (SE)

(72)Inventors:
  • LINDHOLM, Fredrik
    Tokyo 108-0075 (JP)
  • KELLER, Ralf
    52146 Würselen (DE)
  • FERNANDEZ ALONSO, Susana
    E-28009 Madrid (ES)
  • SEDLACEK, Ivo
    250 64 Hovorcovice (CZ)

(74)Representative: Ericsson 
Patent Development Torshamnsgatan 21-23
164 80 Stockholm
164 80 Stockholm (SE)


(56)References cited: : 
WO-A1-2013/151484
WO-A2-2008/117165
WO-A1-2016/074747
US-A1- 2008 008 157
  
  • "IP Multimedia Subsystem (IMS) emergency sessions (Release 12), 3GPP TS 23.167", 3RD GENERATION PARTNERSHIP PROJECT (3GPP) STANDARD, 12 March 2015 (2015-03-12), XP050927712, [retrieved on 2015-03-12]
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

Technical Field



[0001] The present invention relates to emergency calls in an IP multimedia subsystem, IMS, enabled network. In particular, the invention relates to methods and apparatuses for enabling emergency calls for roaming UEs on the network.

Background



[0002] In the context of a cellular telephone network, an unauthenticated mobile emergency call is an emergency call where the identity of the subscriber is not asserted by the network. A call to a Public Safety Answering Point (PSAP), i.e. an emergency centre, where the subscriber's number is not visible, may also be considered an unauthenticated mobile emergency call. Such unauthenticated calls have been permitted in order to allow an emergency call to be made despite normal telephone services being unavailable to a particular user terminal. Unauthenticated calls can occur, for example, where a user has a valid subscription but his operator does not have a roaming agreement with the operator the user is camping on. An example can be when the user is in an area where only his operator's competitor has coverage, or when a user is travelling abroad.

[0003] In contrast, an authenticated emergency call is one where the network verifies the identity (or identities) of the subscriber associated with the UE and indicates the asserted identity to the PSAP. Authenticated calls are preferred as they allow the PSAP operators to call the user in case of disconnection, and to identify the person who made a hoax call.

[0004] Taking Sweden as an example, the number of unauthenticated emergency calls in the year 2000 was of the order of 700000, contributing around 18% of all emergency calls from the mobile networks. Out of these 700000 unauthenticated calls, only 1.5% were made in respect of real emergencies. The possibility of making unauthenticated calls encourages hoax calls, as the callers can effectively remain anonymous. In some countries including the UK, network operators have inhibited unauthenticated calls on mobile networks in an attempt to reduce the number of hoax calls. Of course, this in turn prevents users from making valid emergency calls on those rare occasions when only an unauthenticated terminal is available.

[0005] Current IMS roaming standards allow a user, e.g. in a foreign country, to connect to the IMS of their home network without the need for a SIP interconnect between the home PLMN (HPLMN) and the visited PLMN (VPLMN). When IMS roaming is performed without a SIP interconnect, the UE attaches to a radio network (e.g. E-UTRAN) and a packet core network (e.g. EPC) and makes IMS voice calls using an IMS PDN connection with the P-GW of the HPLMN, without any IMS entity of the VPLMN becoming involved. However, if the roaming UE wishes to make an IMS emergency call, this must be routed via the VPLMN. At this point, a problem occurs. The authenticated IMS emergency call must be preceded by a successful IMS emergency registration with the VPLMN. However, the VPLMN's P-CSCF cannot route the IMS emergency registration to HPLMN's IMS core network due to the lack of SIP interconnect between the HPLMN and VPLMN, and does not have access to the data required to register the UE with the VPLMN itself.

[0006] Therefore, a UE roaming on a network which does not have SIP interconnect with the UE's home network is unable to make authenticated emergency calls. As explained above, authenticated emergency calls are preferable to unauthenticated emergency calls, and some PSAPs refuse to accept unauthenticated emergency calls. Therefore, this is a potentially serious problem.

[0007] 3GPP TS 23.167 describes deriving a non-dialable callback number to include as the UE's identity in the session establishment request.

[0008] WO2013/151484 describes checking if an identity of a user is correlated to the IP address and, if so, replacing an identification of the user by the identity of the user.

Summary



[0009] The present invention provides methods, apparatuses, and computer programs as specified in the independent claims. According to an aspect of the present invention, there is provided a method in a proxy call session control function, P-CSCF, of a visited PLMN of handling an unauthenticated emergency call originating from a roaming user equipment, UE, which is not attached to the P-CSCF. The P-CSCF receives a SIP INVITE request from the UE, the INVITE request relating to the unauthenticated emergency call, and determines an IP address of the UE. The P-CSCF sends an identity query to a policy and charging rules function, PCRF, of the visited PLMN indicating the IP address of the UE and requesting other identifiers of the UE;, and receives one or more other identifiers of the UE from the PCRF. The P-CSCF constructs a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of said other identifiers, inserts the TEL and/or SIP URI into the SIP INVITE request, and sends the SIP INVITE request towards a public safety answering point, PSAP.

[0010] According to a further aspect, there is provided a method in a proxy call session control function, P-CSCF, of a visited PLMN of handling an emergency registration originating from a roaming user equipment, UE, which is not attached to the P-CSCF. The P-CSCF receives a session initiation protocol, SIP, REGISTER request from the UE, the REGISTER request relating to the emergency registration, and determines an IP address of the UE. The P-CSCF sends an identity query to a policy and charging rules function, PCRF, of the visited PLMN indicating that IP address of the UE and requesting other identifiers of the UE, and receives one or more other identifiers of the UE from the PCRF. The P-CSCF obtains a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of said other identities, and sends a 200 OK response to the UE in response to the SIP REGISTER request, the 200 OK response including the TEL and/or SIP URI.

[0011] According to a yet further aspect, there is provided an apparatus configured to operate as a P-CSCF, of a visited PLMN. The apparatus comprises a first transceiver, a second transceiver, a third transceiver, and an unauthenticated emergency call processor. The first transceiver is configured to communicate with a roaming UE. The second transceiver is configured to communicate with a PCRF, of the visited PLMN. The third transceiver is configured to communicate with a PSAP. The unauthenticated emergency call processor is configured to:

receive, from the UE via the first transceiver, a session initiation protocol, SIP, INVITE request relating to an unauthenticated emergency call;

determine an IP address of the UE;

send an identity query to the PCRF via the second transceiver, indicating the IP address of the UE and requesting other identifiers of the UE;

receive one or more other identifiers of the UE from the PCRF via the second transceiver;

construct a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of the other identifiers;

insert the TEL and/or SIP URI into the SIP INVITE request;

send a second SIP INVITE request towards the PSAP, via the third transceiver.



[0012] According to a yet further aspect, there is provided an apparatus configured to operate as a P-CSCF, of a visited PLMN. The apparatus comprises a first transceiver, a second transceiver, and an emergency registration request processor. The first transceiver is configured to communicate with a roaming UE. The second transceiver is configured to communicate with a PCRF, of the visited PLMN. The emergency registration request processor is configured to:

receive, from the UE via the first transceiver, a session initiation protocol, SIP, REGISTER request relating to an emergency registration;

determine an IP address of the UE;

send an identity query to the PCRF via the second transceiver, indicating the IP address of the UE and requesting other identifiers of the UE;

receive one or more other identifiers of the UE from the PCRF via the second transceiver;

obtain a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of the other identifiers;

send a 200 OK response to the UE in response to the SIP REGISTER request via the second transceiver, the 200 OK response including the TEL and/or SIP URI.



[0013] According to a final aspect, there is provided a computer program comprising computer readable code which, when run on an apparatus causes the apparatus to perform one of the methods above.

[0014] Further embodiments of the invention are defined in the dependent claims.

Brief Description of the Drawings



[0015] 

Figure 1 is a signalling diagram according to an embodiment;

Figure 2 is a signalling diagram according to a further embodiment;

Figure 3 is a signalling diagram according to a yet further embodiment;

Figure 4 is a flowchart of a method of operating a P-CSCF;

Figure 5 is a flowchart of an alternative method of operating a P-CSCF;

Figure 6 is a flowchart of a method of operating a PCRF;

Figure 7 is a flowchart of a method of operating a UE;

Figure 8 is a schematic diagram of a P-CSCF;

Figure 9 is a schematic diagram of an alternative P-CSCF;

Figure 10 is a schematic diagram of a PCRF; and,

Figure 11 is a schematic diagram of a UE.


Detailed Description



[0016] In order to provide the identity of a roaming UE making an emergency call to the PSAP where no SIP interconnect with the UE's HPLMN exists, methods are proposed below to use the IP address of the UE to identify the UE sufficiently for an authenticated IMS emergency call to take place. Each of these methods relies on the network being able to trust the IP address of the UE, and may therefore be improved by the use of an IP address verification procedure such as that disclosed in WO2013/091735.

[0017] While the methods are intended for use where no SIP interconnect exists between the HPLMN and the VPLMN, it will be appreciated that they could also be used where such a SIP interconnect exists, e.g. as a fallback to conventional methods in case communication with a node of the HPLMN fails.

[0018] A first method is shown in Figure 1. This method relates to the case where the UE attempts to make an unauthenticated IMS emergency call.

[0019] The UE sends a SIP INVITE to the P-CSCF. The SIP INVITE is for an unauthenticated IMS emergency call (e.g. containing an SOS URN in the recipient field). The P-CSCF retrieves the IP address of the UE from the SIP INVITE (for example, the source IP of the IP packet carrying the SIP INVITE request). The PCSCF then sends an AAA request to the PCRF, including the IP address, indicating that the request relates to an emergency call, and requesting other identities for the UE.

[0020] The PCRF sends a resource allocation request (RAR) to the PGW, which reserves resources for the emergency call and sends a resource allocation answer (RAA) to the PCRF. The PCRF uses the IP address of the UE to look up other identities for the UE, for example the IMSI, IMEI, and MSISDN of the UE registered with the IP-CAN. The PCRF includes these identities in an AAA response to the P-CSCF.

[0021] The P-CSCF uses the received identities to create a TEL and/or SIP URI for the UE. The process of creating the SIP URI will be explained in more detail later. The P-CSCF then sends the SIP INVITE to the E-CSCF, adding the URI for the UE into the "P-asserted-identity" field and thus providing the asserted identity of subscriber at the UE. The E-CSCF then proceeds to handle the emergency call as in current standards.

[0022] In this way, the PSAP is provided with a TEL and/or SIP URI which can be used to contact the UE, even in the case where the UE makes an unauthenticated IMS emergency call.

[0023] In this case, there is little disadvantage to a UE making an unauthenticated emergency call rather than an authenticated emergency call, and so the UE may be configured to respond to a failed attempt at emergency registration by immediately making an unauthenticated emergency call. The error response sent by the P-CSCF when the registration fails may indicate that the UE should do this.

[0024] Signalling for the second method is shown in Figure 2. This method relates to the case where the UE is performing an emergency registration in order to make an authenticated IMS emergency call.

[0025] The UE sends a SIP REGISTER request to the P-CSCF, indicating that it is an emergency registration. The P-CSCF determines that no home network is available for the UE, either because it is aware that no SIP interconnect exists for the UE's HPLMN, or following a failure to contact the S-CSCF of the UE's HPLMN. The P-CSCF retrieves the IP address of the UE from the SIP REGISTER (for example, the source IP of the IP packet carrying the SIP INVITE request). The PCSCF then sends an AAA request to the PCRF, including the IP address, indicating that the request relates to an emergency call, and requesting other identities for the UE.

[0026] The PCRF uses the IP address of the UE to look up other identities for the UE, for example the IMSI, IMEI, and MSISDN of the UE registered with the IP-CAN. The PCRF includes these identities in an AAA response to the P-CSCF.

[0027] The P-CSCF uses the received identities to create a TEL and/or SIP URI for the UE. The process of creating the URI will be explained in more detail later. The P-CSCF includes the URI in the P-associated-URI field of a 200OK response sent to the UE in response to the SIP REGISTER.

[0028] In order for this method to work, the UE must accept the 200 OK response without receiving the 410 response which would normally precede it when registering with the IMS. Also, the UE should accept the 200OK response without requiring authentication of the P-CSCF or that an IPSec secure association is set up, as both of these procedures require data that is held in the HPLMN. Given that this procedure is only to be used in an emergency, it is anticipated that the lack of security is acceptable in this case.

[0029] Once the UE has received the 200OK response, it is registered with the IMS, and can make the emergency call as in current standards (except that as no IPSec secure association is set up, the signalling will not be encrypted under that association).

[0030] The signalling for the third method is shown in Figure 3. The third method is similar to the second method, except that the registration is performed at the E-CSCF or S-CSCF of the VPLMN, rather than at the P-CSCF. After constructing the TEL and/or SIP URI, the P-CSCF sends the SIP REGISTER request to the E/S-CSCF, and includes the TEL and/or SIP URI for the UE (e.g. the IMSI, IMEI, and MSISDN). The E/S-CSCF sends a 200 OK message with P-Associated-URI fields containing the URIs received from the P-CSCF, to the UE via the P-CSCF. Alternatively, the P-CSCF may send the SIP REGISTER request to the E-CSCF prior to constructing the TEL and/or SIP URI, and the E-CSCF will return a 200OK message without any user identity in the P-Associated-URI fields. The P-CSCF then constructs the TEL and/or SIP URI and inserts the TEL and/or SIP URI into the P-Associated-URI fields of the 200OK response before sending the 200OK response to the UE. As a further alternative, the P-CSCF may provide the other identities for the UE to the E-CSCF in the SIP REGISTER message, and the E-CSCF may construct the TEL and/or SIP URI and insert it into the P-Associated-URI fields of a 200OK response sent to the UE via the P-CSCF. Depending on the identities of the UE received from the PCRF, a valid TEL or SIP URI may be constructed for the UE in a variety of ways.

[0031] As a first option, if the MSISDN and IMSI of the UE are available, the MNC and MCC codes can be extracted from the IMSI, and the MSISDN can be converted into a global E.164 number. This can be used to construct a SIP URI for the UE of the form "[E.164]@ims.mnc[MNC].mcc[MCC].3gppnetwork.org". For example, if the MSISDN is 12125551212, and the IMSI is 234150999999999 then the SIP URI will be sip:+12125551212@ims.mnc015.mcc234.3gppnetwork.org;user=phone .

[0032] As a second option, if the MSISDN and the IMSI of the UE are available, the MNC and MCC codes can be extracted from the IMSI, and the MSISDN can be converted into a global E.164 number. The P-CSCF can then map the MNC and MCC codes onto a domain name using a mapping table which has previously been provided to the P-CSCF, and form a SIP URI using the global E.164 number and the domain name. For example, if the MSISDN is 12125551212, the IMSI is 234150999999999 and mapping table contains "ims.HPLMNoperator.com" for mnc==015 and mcc==234, then the SIP URI will be sip:+12125551212@ims.HPLMNoperator.com;user=phone .

[0033] As a third option, if only the IMSI is available, the P-CSCF can create a temporary IMPU for the UE based on the IMSI, as described in 3GPP TS 23.003 v 13.1.0, subclause 13.4B. The temporary IMPU is a SIP URI constructed in the form "[IMSI]@ims.mnc[MNC].mcc[MCC].3gppnetwork.org". For example, if the IMSI is 234150999999999, then the temporary IMPU will be sip:234150999999999@ ims.mnc015.mcc234.3gppnetwork.org.

[0034] A TEL URI may be constructed directly from the MSISDN.

[0035] Each of these options provides an identity which the PSAP can use to contact the UE if required, and which is sufficient to allow the UE to attach to the P-CSCF for the second or third methods presented above.

[0036] Figure 4 is a flowchart showing a method of operating a P-CSCF. The P-CSCF receives (S101) a SIP INVITE request from the UE relating to an unauthenticated emergency call. The P-CSCF then determines (S102) an IP address of the UE, and sends (S103) an identity query to the PCRF indicating the IP address and requesting other identifiers for the UE. The P-CSCF receives (S104) one or more identifiers from the P-CSCF, and constructs (S105) a TEL and/or SIP URI for the UE on the basis of at least one of the identifiers. The P-CSCF then inserts (S106) the URI into the SIP INVITE request, and sends (S106) the SIP INVITE request to a PSAP.

[0037] Figure 5 is a flowchart showing a method of operating a P-CSCF. The P-CSCF receives (S201) a SIP REGISTER request from the UE relating to an emergency registration. The P-CSCF determines (S202) an IP address of the UE and sends (S203) an identity query to the PCRF indicating the IP address and requesting other identifiers for the UE. The P-CSCF receives (S204) one or more identifiers from the PCRF, and obtains (S205) a TEL and/or SIP URI on the basis of at least one of the identifiers. The P-CSCF then sends (S206) a 200OK response to the UE, including the TEL and/or SIP URI for the UE.

[0038] Figure 6 is a flowchart showing a method of operating a PCRF for handling an emergency IMS call. The PCRF receives (S301) an identity request comprising an IP address for a UE from a P-CSCF. The PCRF maps (S302) the IP address of the UE to one or more other identifiers of the UE and sends (S303) the other identifiers to the P-CSCF.

[0039] Figure 7 is a flowchart showing a method of operating a UE. The UE sends (S401) a SIP REGISTER request to the P-CSCF of a visited PLMN. In response, the UE receives (S402) an error response from the P-CSCF. The UE then sends (S403) a SIP INVITE request relating to an unauthenticated IMS emergency call to the P-CSCF.

[0040] Figure 8 is a schematic diagram of an apparatus configured to operate as a P-CSCF (100). The apparatus comprises a first transceiver (101), a second transceiver (102), a third transceiver (103), and an unauthenticated emergency call processor (104). The first transceiver (101) is configured to communicate with a roaming UE. The second transceiver (102) is configured to communicate with a PCRF. The third transceiver (103) is configured to communicate with a PSAP. The unauthenticated emergency call processor (104) is configured to:

receive, from the UE via the first transceiver, a session initiation protocol, SIP, INVITE request relating to an unauthenticated emergency call;

determine an IP address of the UE;

send an identity query to the PCRF via the second transceiver, indicating the IP address of the UE and requesting other identifiers of the UE;

receive one or more other identifiers of the UE from the PCRF via the second transceiver;

construct a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of the other identifiers;

insert the URI into the SIP INVITE request;

send a second SIP INVITE request to the PSAP, via the third transceiver.



[0041] Figure 9 is a schematic diagram of an apparatus configured to operate as a P-CSCF (200). The apparatus comprises a first transceiver (201), a second transceiver (202), and an emergency registration request processor (203). The first transceiver (201) is configured to communicate with a roaming UE. The second transceiver (202) is configured to communicate with a PCRF. The emergency registration request processor (203) is configured to:

receive, from the UE via the first transceiver, a session initiation protocol, SIP, REGISTER request relating to an emergency registration;

determine an IP address of the UE;

send an identity query to the PCRF via the second transceiver, indicating the IP address of the UE and requesting other identifiers of the UE;

receive one or more other identifiers of the UE from the PCRF via the second transceiver;

obtain a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of the other identifiers;

send a 200 OK response to the UE in response to the SIP REGISTER request via the second transceiver, the 200 OK response including the URI.



[0042] Figure 10 is a schematic diagram of an apparatus configured to operate as a PCRF (300). The apparatus comprises a transceiver (301) and an identity request processor (302). The transceiver (301) is configured to communicate with a P-CSCF. The identity request processor (302) is configured to:

receive an identity request from the P-CSCF via the transceiver, the identity request comprising an IP address for a user equipment, UE;

map the IP address of the UE to one or more other identifiers of the UE;

send the other identifiers to the P-CSCF via the transceiver.



[0043] Figure 11 is a schematic diagram of an apparatus configured to operate as a UE (400). The apparatus comprises a transceiver (401) and an emergency call processor (402). The transceiver (401) is configured to communicate with an IMS network comprising a P-CSCF, wherein the UE is roaming on the IMS network. The emergency call processor (402) is configured to:

send a SIP REGISTER request relating to an emergency registration to the P-CSCF via the transceiver;

receive an error response from the P-CSCF via the transceiver;

send a SIP INVITE request relating to an unauthenticated emergency call to the P-CSCF via the transceiver.



[0044] The methods described above may be implemented by a computer program which, when run on an apparatus, causes the apparatus to perform the method.

[0045] Although the invention has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the invention, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.


Claims

1. A method in a proxy call session control function, P-CSCF, of a visited PLMN, which does not have SIP interconnect with a user equipment's home network, of handling an unauthenticated emergency call originating from the roaming user equipment, UE, which is not attached to the P-CSCF, the method comprising:

receiving a SIP INVITE request from the UE, the INVITE request relating to the unauthenticated emergency call;

determining an IP address of the UE;

sending an identity query to a policy and charging rules function, PCRF, of the visited PLMN indicating the IP address of the UE and requesting other identifiers of the UE;

receiving one or more other identifiers of the UE from the PCRF;

constructing a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of said other identifiers;

inserting the TEL and/or SIP URI into the SIP INVITE request;

sending the SIP INVITE request towards a public safety answering point, PSAP.


 
2. A method according to claim 1, wherein a received identifier is an IMSI and the step of constructing the SIP URI comprises constructing a temporary IMPU based on the IMSI.
 
3. A method according to claim 1, wherein received identifiers are an IMSI and an MSISDN and the step of constructing the SIP URI comprises:

extracting MNC and MCC codes from the IMSI; and

constructing a SIP URI from the MSISDN and the MNC and MCC codes.


 
4. A method according to claim 3, wherein constructing the SIP URI from the MSISDN and the MNC and MCC codes comprises:

converting the MSISDN to a global E.164 number;

constructing a SIP URI of the form:
"[E.164 number]@ims.mnc[MNC].mcc[MCC].3gppnetwork.org".


 
5. A method according to claim 3, wherein constructing the SIP URI from the MSISDN and the MNC and MCC codes comprises:

mapping the MNC and MCC to a domain name using a mapping table in the P-CSCF;

converting the MSISDN to a global E.164 number;

constructing a SIP URI from the global E.164 number and the domain name.


 
6. A method according to claim 1, wherein a received identifier is an IMSI, and the step of constructing the SIP URI comprises:
if another received identifier is an MSISDN, constructing the SIP URI according to any of claims 3 to 5, otherwise constructing the SIP URI according to claim 2.
 
7. A method according to any of claims 1 to 6, wherein a received identifier is an MSISDN, the step of constructing the TEL URI comprises constructing the TEL URI from the MSISDN.
 
8. A method according to any of claims 1 to 7,wherein determining the IP address of the UE comprises determining a source IP address of an IP packet containing the SIP INVITE.
 
9. A method in a proxy call session control function, P-CSCF, of a visited PLMN, which does not have SIP interconnect with a user equipment's home network, of handling an emergency registration originating from the roaming user equipment, UE, which is not attached to the P-CSCF, the method comprising:

receiving a session initiation protocol, SIP, REGISTER request from the UE, the REGISTER request relating to the emergency registration;

determining an IP address of the UE;

sending an identity query to a policy and charging rules function, PCRF, of the visited PLMN indicating that IP address of the UE and requesting other identifiers of the UE;

receiving one or more other identifiers of the UE from the PCRF;

obtaining a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of said other identities;

sending a 200 OK response to the UE in response to the SIP REGISTER request, the 200 OK response including the TEL and/or SIP URI.


 
10. A method according to claim 9, wherein obtaining the TEL and/or SIP URI comprises sending a second SIP REGISTER request to an emergency call session control function, E-CSCF, the second SIP REGISTER request identifying the UE and containing at least one of the other identities; and receiving a 200 OK response from the E-CSCF, the 200 OK response including the TEL and/or SIP URI.
 
11. Apparatus configured to operate as a proxy call session control function, P-CSCF, of a visited PLMN, which does not have SIP interconnect with a user equipment's home network, the apparatus comprising:

a first transceiver configured to communicate with the roaming user equipment, UE;

a second transceiver configured to communicate with a policy and charging rules function, PCRF, of the visited PLMN;

a third transceiver configured to communicate with a public safety answering point, PSAP;

an unauthenticated emergency call processor configured to:

receive, from the UE via the first transceiver, a session initiation protocol, SIP, INVITE request relating to an unauthenticated emergency call;

determine an IP address of the UE;

send an identity query to the PCRF via the second transceiver, indicating the IP address of the UE and requesting other identifiers of the UE;

receive one or more other identifiers of the UE from the PCRF via the second transceiver;

construct a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of the other identifiers;

insert the TEL and/or SIP URI into the SIP INVITE request;

send the SIP INVITE request towards a public safety answering point, PSAP, via the third transceiver.


 
12. Apparatus configured to operate as a proxy call session control function, P-CSCF, of a visited PLMN, which does not have SIP interconnect with the user equipment's home network, the apparatus comprising:

a first transceiver configured to communicate with the roaming user equipment, UE;

a second transceiver configured to communicate with a policy and charging rules function, PCRF, of the visited PLMN;

an emergency registration request processor configured to:

receive, from the UE via the first transceiver, a session initiation protocol, SIP, REGISTER request relating to an emergency registration;

determine an IP address of the UE;

send an identity query to the PCRF via the second transceiver, indicating the IP address of the UE and requesting other identifiers of the UE;

receive one or more other identifiers of the UE from the PCRF via the second transceiver;

obtain a TEL and/or SIP uniform resource identifier, URI, for the UE on the basis of at least one of the other identifiers;

send a 200 OK response to the UE in response to the SIP REGISTER request via the second transceiver, the 200 OK response including the TEL and/or SIP URI.


 
13. A computer program comprising computer readable code which, when run on an apparatus, causes the apparatus to perform a method according to any of claims 1 to 10.
 


Ansprüche

1. Verfahren in einer Vertretungsanrufs-Sitzungs-Kontrollfunktion, P-CSCF, eines besuchten PLMN, das keine SIP-Verbindung mit einem Heimnetzwerk der Benutzerausrüstung hat, zum Handhaben eines nicht authentifizierten Notrufs mit Ursprung in der Benutzerausrüstung in Roaming, UE, die nicht an der P-CSCF angebracht ist, wobei das Verfahren umfasst:

Empfangen einer SIP-INVITE-Anfrage von der UE, wobei sich die INVITE-Anfrage auf den nicht authentifizierten Notruf bezieht;

Bestimmen einer IP-Adresse der UE;

Senden einer Identitätsabfrage an eine Vorschriften- und Gebührenregelfunktion, PCRF, des besuchten PLMN unter Angabe der IP-Adresse der UE und Anfordern von anderen Identifizierungselemente der UE;

Empfangen von einem oder mehreren andere Identifizierungselementen der UE von der PCRF;

Erstellen eines einheitlichen Identifizierungselements für TEL- und/oder SIP-Ressourcen, URI, für die UE auf der Grundlage von mindestens einem der anderen Identifizierungselemente;

Einsetzen der TEL- und/oder SIP-URI in die SIP-INVITE-Anfrage;

Senden der SIP-INVITE-Anfrage an einen öffentlichen Sicherheits-Antwortpunkt, PSAP.


 
2. Verfahren nach Anspruch 1, wobei ein empfangenes Identifizierungselement eine IMSI ist, und der Schritt des Erstellens der SIP-URI Erstellen einer temporären IMPU, die auf der IMSI basiert, umfasst.
 
3. Verfahren nach Anspruch 1, wobei die empfangen Identifizierungselemente eine IMSI und eine MSISDN sind, und der Schritt des Erstellens der SIP-URI umfasst:

Extrahieren von MNC- und MCC-Codes aus der IMSI; und

Erstellen einer SIP-URI aus der MSISDN und den MNC- und MCC-Codes.


 
4. Verfahren nach Anspruch 3, wobei das Erstellen der SIP-URI aus der MSISDN und den MNC- und MCC-Codes umfasst:

Umwandeln der MSISDN in eine globale E.164-Nummer;

Erstellen einer SIP-URI in der Form:
"[E.164 number]@ims.mnc[MNC].mcc[MCC].3gppnetwork.org".


 
5. Verfahren nach Anspruch 3, wobei das Erstellen der SIP-URI aus der MSISDN und den MNC- und MCC-Codes umfasst:

Zuordnen des MNC und MCC zu einem Domainnamen unter Verwendung einer Zuordnungstabelle in der P-CSCF;

Umwandeln der MSISDN in eine globale E.164-Nummer;

Erstellen einer SIP-URI aus der globalen E.164-Nummer und dem Domainnamen.


 
6. Verfahren nach Anspruch 1, wobei ein empfangenes Identifizierungselement eine IMSI ist, und der Schritt des Erstellens der SIP-URI umfasst:
wenn ein anderes empfangenes Identifizierungselement eine MSISDN ist, Erstellen der SIP-URI nach einem der Ansprüche 3 bis 5, anderenfalls Erstellen der SIP-URI nach Anspruch 2.
 
7. Verfahren nach einem der Ansprüche 1 bis 6, wobei ein empfangenes Identifizierungselement eine MSISDN ist, und der Schritt des Erstellens der TEL-URI Erstellen der TEL-URI aus der MSISDN umfasst.
 
8. Verfahren nach einem der Ansprüche 1 bis 7, wobei das Bestimmen der IP-Adresse der UE Bestimmen einer Quellen-IP-Adresse eines IP-Pakets, das die SIP-INVITE enthält, umfasst.
 
9. Verfahren in einer Vertretungsanrufs-Sitzungs-Kontrollfunktion, P-CSCF, eines besuchten PLMN, das keine SIP-Verbindung mit einem Heimnetzwerk der Benutzerausrüstung hat, zum Handhaben einer Notfallregistrierung mit Ursprung in der Benutzerausrüstung in Roaming, UE, die nicht an dem P-CSCF angebracht ist, wobei das Verfahren umfasst:

Empfangen eines Sitzungseinleitungsprotokolls, SIP, REGISTER-Anfrage von der UE, wobei die REGISTER-Anfrage auf die Notfallregistrierung bezieht;

Bestimmen einer IP-Adresse der UE;

Senden einer Identitätsabfrage an eine Vorschriften- und Gebührenregelfunktion, PCRF, des besuchten PLMN unter Angabe der IP-Adresse der UE und Anfordern von anderen Identifizierungselementen der UE;

Empfangen von einem oder mehreren andere Identifizierungselementen der UE von der PCRF;

Erhalten eines einheitlichen Identifizierungselements für TEL- und/oder SIP-Ressourcen, URI, für die UE auf der Grundlage von mindestens einer der anderen Identitäten;

Senden einer 200-OK-Antwort an die UE als Antwort auf die SIP-REGISTER-Anfrage, wobei die 200-OK-Antwort die TEL- und/oder SIP-URI einschließt.


 
10. Verfahren nach Anspruch 9, wobei das Erhalten der TEL- und/oder SIP-URI Senden einer zweiten SIP-REGISTER-Anfrage an eine Notruf-Sitzungs-Kontrollfunktion, E-CSCF, umfasst, wobei die zweite SIP-REGISTER-Anfrage die UE identifiziert und mindestens eine der anderen Identitäten enthält; und Empfangen einer 200-OK-Antwort von der E-CSCF, wobei die 200-OK-Antwort die TEL- und/oder SIP-URI einschließt.
 
11. Einrichtung, die ausgelegt ist, um als eine Vertretungsanrufs-Sitzungs-Kontrollfunktion, P-CSCF, eines besuchten PLMN, das keine SIP-Verbindung mit einem Heimnetzwerk der Benutzerausrüstung hat, zu funktionieren, wobei die Einrichtung umfasst:

einen ersten Sender/Empfänger, der ausgelegt ist, um mit der Benutzerausrüstung in Roaming, UE, zu kommunizieren;

einen zweiten Sender/Empfänger, der ausgelegt ist, um mit einer Vorschriften- und Gebührenregelfunktion, PCRF, des besuchten PLMN zu kommunizieren;

einen dritten Sender/Empfänger, der ausgelegt ist, um mit einem öffentlichen Sicherheits-Antwortpunkt, PSAP, zu kommunizieren;

einen Prozessor für nicht authentifizierte Notrufe, der ausgelegt ist, um:

von der UE über den ersten Sender/Empfänger ein Sitzungseinleitungsprotokoll, SIP, INVITE-Anfrage bezogen auf einen nicht authentifizierten Notruf zu erhalten;

eine IP-Adresse der UE zu bestimmen;

eine Identitätsabfrage an die PCRF über den zweiten Sender/Empfänger zu senden, unter Angabe der IP-Adresse der UE und Anfordern von andere Identifizierungselementen der UE;

eines oder mehrere andere Identifizierungselemente der UE von der PCRF über den zweiten Sender/Empfänger zu empfangen;

ein einheitliches Identifizierungselements für TEL- und/oder SIP-Ressourcen, URI, für die UE auf der Grundlage von mindestens einem der anderen Identifizierungselemente zu erstellen;

die TEL- und/oder SIP-URI in die SIP-INVITE-Anfrage einzusetzen;

die SIP-INVITE-Anfrage an einen öffentlichen Sicherheits-Antwortpunkt, PSAP, über den dritten Sender/Empfänger zu senden.


 
12. Einrichtung, die ausgelegt ist, um als eine Vertretungsanrufs-Sitzungs-Kontrollfunktion, P-CSCF, eines besuchten PLMN, das keine SIP-Verbindung mit einem Heimnetzwerk der Benutzerausrüstung hat, zu funktionieren, wobei die Einrichtung umfasst:

einen ersten Sender/Empfänger, der ausgelegt ist, um mit der Benutzerausrüstung in Roaming, UE, zu kommunizieren;

einen zweiten Sender/Empfänger, der ausgelegt ist, um mit einer Vorschriften- und Gebührenregelfunktion, PCRF, des besuchten PLMN zu kommunizieren;

einen Prozessor für nicht authentifizierte Notrufe, der ausgelegt ist, um:

von der UE über den ersten Sender/Empfänger ein Sitzungseinleitungsprotokoll, SIP, REGISTER-Anfrage bezogen auf einen nicht authentifizierten Notruf zu empfangen;

eine IP-Adresse der UE zu bestimmen;

eine Identitätsabfrage an die PCRF über den zweiten Sender/Empfänger zu senden, unter Angabe der IP-Adresse der UE und Anfordern von andere Identifizierungselementen der UE;

eines oder mehrere andere Identifizierungselemente der UE von der PCRF über den zweiten Sender/Empfänger zu empfangen;

ein einheitliches Identifizierungselements für TEL- und/oder SIP-Ressourcen, URI, für die UE auf der Grundlage von mindestens einem der anderen Identifizierungselemente zu erhalten;

eine 200-OK-Antwort an das UE als Antwort auf die SIP-REGISTER-Anfrage über den zweiten Sender/Empfänger zu senden, wobei die 200-OK-Antwort die TEL und/oder SIP-URI einschließt.


 
13. Computerprogramm, umfassend computerlesbaren Code, der, wenn er auf einer Einrichtung läuft, verursacht, dass die Einrichtung ein Verfahren nach einem der Ansprüche 1 bis 10 ausführt.
 


Revendications

1. Procédé, dans une fonction de commande de session d'appel mandataire, P-CSCF, d'un PLMN visité qui ne dispose pas d'interconnexion SIP avec un réseau domestique d'équipement d'utilisateur, pour traiter un appel d'urgence non authentifié provenant de l'équipement d'utilisateur itinérant, UE, qui n'est pas rattaché à la P-CSCF, le procédé comprenant les étapes consistant à :

recevoir une demande SIP INVITE de l'UE, la demande INVITE concernant l'appel d'urgence non authentifié ;

déterminer une adresse IP de l'UE ;

envoyer d'une interrogation d'identité à une fonction de politique et de règles de facturation, PCRF, du PLMN visité, indiquant l'adresse IP de l'UE et demandant d'autres identifiants de l'UE ;

recevoir un ou plusieurs autres identifiants de l'UE en provenance de la PCRF ;

construire un identifiant de ressources uniformes de type TEL et/ou SIP, URI, pour l'UE sur la base d'au moins un desdits autres identifiants ;

insérer l'URI de type TEL et/ou SIP dans la demande SIP INVITE ;

envoyer la demande SIP INVITE vers un point de réponse de sécurité publique, PSAP.


 
2. Procédé selon la revendication 1, dans lequel un identifiant reçu est un IMSI et l'étape de construction de l'URI de SIP comprend la construction d'une IMPU temporaire sur la base de l'IMSI.
 
3. Procédé selon la revendication 1, dans lequel les identifiants reçus sont un IMSI et un MSISDN et l'étape de construction de l'URI de type SIP comprend les étapes consistant à :

extraire des codes MNC et MCC de l'IMSI ; et

construire un URI de type SIP à partir du MSISDN et des codes MNC et MCC.


 
4. Procédé selon la revendication 3, dans lequel la construction de l'URI de type SIP à partir du MSISDN et des codes et MNC et MCC comprend les étapes consistant à :

convertir le MSISDN en un numéro E.164 global ;

construire un URI de type SIP de la forme :
« [Numéro E.164]@ims.mnc[MNC].mcc[MCC].3gppnetwork.org ».


 
5. Procédé selon la revendication 3, dans lequel la construction de l'URI de type SIP à partir du MSISDN et des codes MNC et MCC comprend les étapes consistant :

mettre en correspondance le MNC et le MCC par rapport à un nom de domaine en utilisant une table de mise en correspondance dans la P-CSCF ;

convertir le MSISDN en un numéro E.164 global ;

construire un URI de type SIP à partir du numéro E.164 global et du nom de domaine.


 
6. Procédé selon la revendication 1, dans lequel un identifiant reçu est un IMSI, et l'étape de construction de l'URI de type SIP comprend :
si un autre identifiant reçu est un MSISDN, la construction de l'URI de type SIP selon l'une quelconque des revendications 3 à 5, sinon la construction de l'URI de type SIP selon la revendication 2.
 
7. Procédé selon l'une quelconque des revendications 1 à 6, dans lequel un identifiant reçu est un MSISDN, et l'étape de construction de l'URI de type TEL comprend la construction de l'URI de type TEL à partir du MSISDN.
 
8. Procédé selon l'une quelconque des revendications 1 à 7, dans lequel la détermination de l'adresse IP de l'UE comprend la détermination d'une adresse IP source d'un paquet IP contenant le message SIP INVITE.
 
9. Procédé dans une fonction de commande de session d'appel mandataire, P-CSCF, d'un PLMN visité qui ne dispose pas d'une interconnexion SIP avec le réseau domestique d'équipement d'utilisateur, pour traiter un enregistrement d'urgence provenant de l'équipement d'utilisateur itinérant, UE, qui n'est pas attaché à la P-CSCF, le procédé comprenant les étapes consistant à :

recevoir un protocole d'ouverture de session, SIP, une demande REGISTER à partir de l'UE, la demande REGISTER concernant l'enregistrement d'urgence ;

déterminer une adresse IP de l'UE ;

envoyer d'une interrogation d'identité à une fonction de politique et de règles de facturation, PCRF, du PLMN visité, indiquant cette adresse IP de l'UE et demandant d'autres identifiants de l'UE ;

recevoir un ou plusieurs autres identifiants de l'UE à partir de la PCRF ;

obtenir un identifiant de ressource uniforme de type TEL et/ou SIP, URI, pour l'UE sur la base d'au moins une desdites autres identités ;

envoyer une réponse 200 OK à l'UE en réponse à la demande SIP REGISTER, la réponse 200 OK incluant l'URI de type TEL et/ou SIP.


 
10. Procédé selon la revendication 9, dans lequel l'obtention de l'URI de type TEL et/ou SIP comprend l'envoi d'une seconde demande SIP REGISTER à une fonction de commande de session d'appel d'urgence, E-CSCF, la seconde demande SIP REGISTER identifiant l'UE et contenant au moins une des autres identités ; et recevoir une réponse 200 OK à partir de la E-CSCF, la réponse 200 OK incluant l'URI de type TEL et/ou SIP.
 
11. Appareil configuré pour fonctionner en tant que fonction de commande de session d'appel mandataire, P-CSCF, d'un PLMN visité, qui ne dispose pas d'interconnexion SIP avec le réseau domestique d'équipement utilisateur, l'appareil comprenant :

un premier émetteur-récepteur configuré pour communiquer avec l'équipement d'utilisateur itinérant, UE ;

un deuxième émetteur-récepteur configuré pour communiquer avec une fonction de politique et de règles de facturation, PCRF, du PLMN visité ;

un troisième émetteur-récepteur configuré pour communiquer avec un point de réponse de sécurité publique, PSAP ;

un processeur d'appel d'urgence non authentifié configuré pour :

recevoir, à partir de l'UE via le premier émetteur-récepteur, un protocole d'ouverture de session, SIP, une demande INVITE concernant un appel d'urgence non authentifié ;

déterminer une adresse IP de l'UE ;

envoyer une demande d'identité à la PCRF via le deuxième émetteur-récepteur, en indiquant l'adresse IP de l'UE et en demandant d'autres identifiants de l'UE ;

recevoir un ou plusieurs autres identifiants de l'UE à partir de la PCRF via le deuxième émetteur-récepteur ;

construire un identifiant de ressource uniforme de type TEL et/ou SIP, URI, pour l'UE sur la base d'au moins un des autres identifiants ;

insérer l'URI de type TEL et/ou SIP dans la demande SIP INVITE ;

envoyer la demande SIP INVITE vers un point de réponse de sécurité publique, PSAP, via le troisième émetteur-récepteur.


 
12. Appareil configuré pour fonctionner comme une fonction de commande de session d'appel mandataire, P-CSCF, d'un PLMN visité, qui ne dispose pas d'interconnexion SIP avec le réseau domestique d'équipement utilisateur, l'appareil comprenant :

un premier émetteur-récepteur configuré pour communiquer avec l'équipement d'utilisateur itinérant, UE ;

un second émetteur-récepteur configuré pour communiquer avec une fonction de politique et de règles de facturation, PCRF, du PLMN visité ;

un processeur de demande d'enregistrement d'urgence configuré pour :

recevoir, à partir de l'UE via le premier émetteur-récepteur, un protocole d'ouverture de session, SIP, une demande REGISTER concernant un enregistrement d'urgence ;

déterminer une adresse IP de l'UE ;

envoyer une demande d'identité à la PCRF via le deuxième émetteur-récepteur, en indiquant l'adresse IP de l'UE et en demandant d'autres identifiants de l'UE ;

recevoir un ou plusieurs autres identifiants de l'UE à partir de la PCRF via le deuxième émetteur-récepteur ;

obtenir un identifiant de ressource uniforme de type TEL et/ou SIP, URI, pour l'UE sur la base d'au moins un des autres identifiants ;

envoyer une réponse 200 OK à l'UE en réponse à la demande SIP REGISTER, via le deuxième émetteur-récepteur, la réponse 200 OK incluant l'URL de type TEL et/ou SIP.


 
13. Programme informatique comprenant un code lisible par ordinateur qui, lorsqu'il est exécuté sur un appareil, amène l'appareil à exécuter un procédé selon l'une quelconque des revendications 1 à 10.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description