WO2020064117A1

WO2020064117A1 - Method, apparatus and computer program for emergency data session handover

Info

Publication number: WO2020064117A1
Application number: PCT/EP2018/076402
Authority: WO
Inventors: Ashok Kumar Nayak
Original assignee: Nokia Technologies Oy
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-04-02

Abstract

An apparatus comprising means for performing: receiving a first message at the apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM FOR EMERGENCY DATA SESSION HANDOVER

Technical Field

Various examples relate to a method, apparatus and a computer program. More particularly, various examples relate to a handover of a user equipment (UE) between two networks.

Background

Emergency data sessions may be established between devices for important communications, for example for calls to an ambulance, police or fire service.

Summary

According to a first aspect, there is provided an apparatus comprising means for performing: receiving a first message at the apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session. According to some examples, the means are further configured to perform: giving priority to the emergency data session over other data sessions.

According to some examples, the apparatus is configured such that the giving priority to the emergency data session over other data sessions comprises maintaining the emergency data session in a situation where the apparatus is overloaded.

According to some examples, the indication is comprised in a header field of the message.

According to some examples, the header field is a Resource-Priority. According to some examples, the means are further configured to perform: determining that the data session is an emergency data session when the header field comprises a predetermined entry.

According to some examples, the predetermined entry comprises a predetermined namespace.

According to some examples, the predetermined namespace is“esnet”.

According to some examples, the means are further configured to perform: sending a second message to a home subscriber server in response to the receiving a first message, the second message comprising a location information request message, wherein the second message comprises information indicating that the second message is a high priority message.

According to some examples, the first message comprises a request universal resource identifier comprising an emergency session transfer number for single radio voice call continuity. According to some examples, the location information request message comprises a session-priority attribute value pair value of PRIORITY-0.

According to some examples, the first message is an invite message.

According to some examples, the indication comprises a value.

According to some examples, the means are further configured to perform: comparing, at the apparatus, the value with a list of values stored at the apparatus; wherein when the value of the indication matches a value in the list the apparatus determines that the data session is an emergency data session.

According to some examples, the means are further configured to perform: forwarding the emergency data session from the apparatus to an address corresponding to the value.

According to some examples, the value is an emergency session transfer number for single radio voice call continuity. According to some examples, the address corresponding to the value is an emergency access transfer function address.

According to some examples, the apparatus comprises am

interrogating call session control function. According to some examples, the first network is a long-term evolution network and the second network is a circuit switched network.

According to some examples, the emergency data session comprises an emergency call.

According to a second aspect, there is provided an apparatus comprising at least one processor; and at least one memory including computer program; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: receiving a first message at the apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to some examples, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: giving priority to the emergency data session over other data sessions.

According to some examples, the header field is a Resource-Priority.

According to some examples, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: determining that the data session is an emergency data session when the header field comprises a predetermined entry.

According to some examples, the predetermined namespace is“esnet”.

According to some examples, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: sending a second message to a home subscriber server in response to the receiving a first message, the second message comprising a location information request message, wherein the second message comprises information indicating that the second message is a high priority message.

According to some examples, the first message comprises a request universal resource identifier comprising an emergency session transfer number for single radio voice call continuity.

According to some examples, the location information request message comprises a session-priority attribute value pair value of PRIORITY-0.

According to some examples, the first message is an invite message. According to some examples, the indication comprises a value.

According to some examples, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: comparing, at the apparatus, the value with a list of values stored at the apparatus; wherein when the value of the indication matches a value in the list the apparatus determines that the data session is an emergency data session.

According to some examples, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: forwarding the emergency data session from the apparatus to an address corresponding to the value. According to some examples, the value is an emergency session transfer number for single radio voice call continuity.

According to some examples, the address corresponding to the value is an emergency access transfer function address. According to some examples, the apparatus comprises am

interrogating call session control function.

According to some examples, the first network is a long-term evolution network and the second network is a circuit switched network.

According to a third aspect there is provided an apparatus comprising: receiving circuitry configured to perform: receiving a first message at the apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining circuitry configured to perform: determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to a fourth aspect there is provided an apparatus comprising means for performing: sending a message to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

According to some examples, the message in an invite message.

According to some examples, the header field is a Resource-Priority header field.

According to some examples, the indication comprises a predetermined entry comprised in the header field. According to some examples, the predetermined entry comprises a predetermined namespace.

According to some examples, the predetermined namespace is“esnet”.

According to some examples, the message comprises a request universal resource identifier comprising an emergency session transfer number for single radio voice call continuity.

According to some examples, the indication comprises a value.

According to some examples, the value is an emergency session transfer number for single radio voice call continuity. According to some examples, the means are further configured to perform: receiving information that the data session is an emergency data session from a mobile management entity.

According to some examples, the apparatus comprises a mobile switching centre. According to some examples, the message is sent to an interrogating call session control function.

According to some examples, the means comprises: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus. According to a fifth aspect, there is provided an apparatus comprising at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:

sending a message to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

According to some examples, the message in an invite message.

According to some examples, the predetermined namespace is“esnet”.

According to some examples, the indication comprises a value.

According to some examples, the value is an emergency session transfer number for single radio voice call continuity.

According to some examples, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform: receiving information that the data session is an emergency data session from a mobile management entity.

According to some examples, the first network is long-term evolution network and the second network is a circuit switched network. According to some examples, the emergency data session comprises an emergency call.

According to a sixth aspect there is provided an apparatus comprising: sending circuitry configured to perform: sending a message to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

According to a seventh aspect there is provided a method comprising: receiving a first message at an apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to some examples, the method comprises giving priority to the emergency data session over other data sessions. According to some examples, the giving priority to the emergency data session over other data sessions comprises maintaining the emergency data session in a situation where the apparatus is overloaded.

According to some examples, the indication is comprised in a header field of the message. According to some examples, the header field is a Resource-Priority header field.

According to some examples, the method comprises determining that the data session is an emergency data session when the header field comprises a predetermined entry. According to some examples, the predetermined entry comprises a predetermined namespace.

According to some examples, the predetermined namespace is“esnet”.

According to some examples, the method comprises sending a second message to a home subscriber server in response to the receiving a first message, the second message comprising a location information request message, wherein the second message comprises information indicating that the second message is a high priority message.

According to some examples, the first message is an invite message. According to some examples, the indication comprises a value, and the method comprises comparing, at the apparatus, the value with a list of values stored at the apparatus; wherein when the value of the indication matches a value in the list the apparatus determines that the data session is an emergency data session. According to some examples, the method comprises forwarding the emergency data session from the apparatus to an address corresponding to the value.

According to some examples, the apparatus comprises an interrogating call session control function.

According to an eighth aspect there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: receiving a first message at an apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to a ninth aspect there is provided a computer program comprising instructions stored thereon for performing at least the following: receiving a first message at an apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to a tenth aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: receiving a first message at an apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to an eleventh aspect there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: receiving a first message at an apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication; determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

According to a twelfth aspect there is provided a method comprising: sending a message from an apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

According to some examples, the message is an invite message. According to some examples, the indication is comprised in a header field of the message.

According to some examples, the header field is a Resource-Priority header field. According to some examples, the indication comprises a predetermined entry comprised in the header field.

According to some examples, the predetermined namespace is“esnet”. According to some examples, the message comprises a request universal resource identifier comprising an emergency session transfer number for single radio voice call continuity.

According to some examples, the indication comprises a value.

According to some examples, the method comprises receiving information that the data session is an emergency data session from a mobile management entity.

According to some examples, the apparatus comprises a mobile switching centre.

According to some examples, the message is sent to an interrogating call session control function.

According to a thirteenth aspect, there is provided a computer program comprising instructions for causing an apparatus to perform at least the following: sending a message from an apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session. According to a fourteenth aspect, there is provided a computer program comprising instructions stored thereon for performing at least the following: sending a message from an apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

According to a fifteenth aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following: sending a message from an apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

According to a sixteenth aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: sending a message from an apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

In the above, various aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above.

Various other aspects and further embodiments are also described in the following detailed description and in the attached claims. Brief Description of the Drawings

To assist understanding of the present disclosure and to show how some embodiments may be put into effect, reference is made by way of example only to the accompanying drawings in which:

Figure 1 shows schematically an example of a system;

Figure 2 shows schematically an example of a message flow;

Figure 3 shows schematically an example of a message flow;

Figure 4 shows schematically an example of a message flow;

Figure 5 shows schematically an example of a message flow;

Figures 6 shows schematically an example of an apparatus;

Figure 7 shows schematically a method according to an example; and

Figure 8 shows schematically a method according to an example.

Detailed Description

Some examples may be provided in the context of emergency data sessions.

Some examples may be provided in the context of handovers of a UE between a first network and a second network.

In some examples the first network is a Long Term Evolution (LTE) network and the second network is a legacy network, such as a Circuit Switched (CS) network.

Figure 1 shows schematically an example system. As shown in Figure 1 , the system may comprise at least one (UE). Figure 1 shows an exemplary system comprising UEs 102a and 102b. The UEs may be mobile terminals. The UEs may be various different examples of mobile

communication devices such as portable digital assistants (PDAs), pagers, mobile televisions, gaming devices, laptop computers, mobile phones, cameras, video recorders, audio/video players, radios, global positioning system (GPS) devices, or any combination of the aforementioned, and other types of voice, text and/or data communications devices. However, it should be understood that a UE as illustrated and hereinafter described is merely illustrative of one type of device that would benefit from embodiments of the present invention and, therefore, should not be taken to limit the scope of the present invention.

The system may also comprise a number a number of different access networks including one or more of GSM/Edge Radio Access Networks

(GERANs), Universal Terrestrial Radio Access Networks (UTRANs) and/or Evolved UTRANs (E-UTRANs) 105, and/or one or more circuit switched networks 101 or the like. Circuit switched networks 101 may comprise a 2G GSM network, for example. These networks may include or otherwise communicate with a Mobility Management Entity (MME) 103 (which may also be configured as a serving GPRS Support Node - SGSN), a Mobile Switching Center (MSC) 104 or the like to route calls, data or the like to and from the UEs via the respective access networks. MME/SGSN (103), MSC (104) and/or UE (102a, 102b) may be coupled to one or more data or Internet Protocol (IP) networks 107, such as one or more local area networks, wide area networks, etc.. The IP network may, in turn, be coupled to a 3rd

Generation Partnership Program (3GPP) IP Multimedia Subsystem (IMS) 109. These networks and components may cooperate to enable support for an eSRVCC (enhanced single radio voice call continuity) emergency call session with a public safety answering point (PSAP) 110 in accordance with example embodiments of the present invention.

In the system of Figure 1 , entities shown below MME/SGSN 103 in the figure may be considered part of an LTE network e.g. access network 105 may comprise an LTE network.

The IMS 109 may include one or more application servers (AS) 121 and an IMS core with a number of network entities, which may be servers. For example, the IMS core may include a home subscriber server (HSS) configured to function as a master database for a given user (UE 102a or 102b, for example), including subscription-related information to support network entities handling IMS-based calls/sessions. In this regard, the IMS core may also include a number of call session (or state) control functions

(CSCFs) to handle different functions. The CSCFs may be divided into various categories such as a proxy CSCF (P-CSCF) 115, interrogating/serving CSCF (I/S- CSCF) 106 and/or emergency CSCF (E-CSCF) 113. The P-CSCF 115 provides the terminals with a gateway or entry point into the IMS core. The l/S- CSCF 106, which may alternatively be separate components, operates as the authentication contact point within the IMS core for connections to terminals (the interrogating function), and performs the session control services for the terminals, providing the call intelligence and business logic (the serving function). The E-CSCF 113 performs emergency session processing and routing, and may employ a location retrieval function (LRF) 111 to retrieve location information of the UE 102a, 102b that has initiated an emergency session. This information may include, for example, routing information and other parameters necessary for emergency services, which may be subject to local regulation.

The IMS 109 may further include an application server referred to as a domain transfer function (DTF) or service centralization and continuity application server (SCC AS) 119, to which IMS sessions may be anchored to enable service continuity for the user during transition between two access networks. A similar anchoring function in IMS emergency sessions may be provided by an emergency access transfer function (EATF) 124, which may also be referred to as an emergency SCC-AS (E-SCC-AS) 119. In some examples the IMS 109 may also comprise an access transfer control function (ATCF) 117.

The system shown in FIG. 1 supports eSRVCC emergency calls. It should be understood, however, that example embodiments of the present invention may equally support an SRVCC (single radio voice call continuity) emergency call .

SRVCC and eSRVCC functionality is used to attempt to avoid dropping of calls when a UE moves from an LTE domain to a CS domain. When a UE moves to an area where there is no LTE coverage, or if LTE coverage is lost for some reason (such as failure or temporary failure of the LTE network), a data session such as a voice over Internet Protocol (VoIP) session over an LTE network may be transferred to a CS network. This enables relatively new networking LTE technologies to coexist with older legacy network

technologies such as CS networks.

Figure 2 shows a situation in which an example of the invention could be deployed. In Figure 2, an l-CSCF 206 is overloaded. Overload situations may occur where an IMS element does not have enough bandwidth or processing power to process all of the data being transmitted through the IMS. An overload situation may occur, for example, when there is a large amount of data traffic in a localised area. Figure 2 shows an example message flow between UE 202, MSC 204, l-CSCF 206, HSS 208 and PSAP 210. Initially at 212, the UE is engaged in an active emergency data session or an alerting emergency data session with PSAP 210. An active emergency data session may be considered to be an ongoing emergency data session. An alerting emergency data session may be considered to be an emergency data session for which an alert indicating that the start of the emergency data session will take place is being received at UE 202 or PSAP 210. The emergency data session may comprise an emergency data call.

At 214, UE 202 moves from a LTE domain to a circuit switched (CS) domain. This causes MSC 204 to send a message at 216 to l-CSCF 206.

The message may be an invite message. The message may be a domain transfer invite (DT-INVITE) message.

In a situation where an IMS is overloaded, elements in the IMS may drop data packets, which leads to the termination of a data session in the IMS. In the exemplary situation shown in Figure 2, l-CSCF is overloaded. As such, in order to handle the overload situation, at 218 the l-CSCF may drop a packet of the emergency data session established at 212.

Figure 3 shows a situation in which an example of the invention could be deployed. In Figure 3, an HSS 322 is overloaded. Overload situations may occur where an IMS element does not have enough bandwidth or processing power to process all of the data being transmitted through the IMS. Figure 3 shows an example message flow between UE 302, MSC 304, I- CSCF 306, HSS 308 and PSAP 310. Steps 312, 314 and 316 are similar to steps 212, 214 and 216. At step 320, l-CSCF sends a message to HSS 308. The message may be a location information request (LIR) message.

At step 322, the HSS 322 is overloaded and drops a data packet of the emergency data session established at 312. This can lead to termination of the emergency data session.

Figure 4 shows an example of the invention in which an overloaded network uses SRVCC or eSRVCC functionality. Figure 4 shows an example message flow between elements of a network. These elements include UE 402, MSC 404, l-CSCF 406, HSS 408, EATF 424 and PSAP 410. The person skilled in the art will understand that the network may comprise further elements that are not shown in Figure 4.

At 412, an active or alerting emergency data session is established or is in the process of being established between UE 402 and PSAP 410.

At 414, UE 402 moves from an LTE domain to a CS domain, which triggers eSRVCC operation. The process of a handover of UE 402 from the LTE domain to the CS domain is then started.

MSC 404 may be aware (i.e. have information) of which data sessions are emergency data sessions. For example, MSC 404 may receive this information from an MME. The MME may provide information to MSC 404 as to which data sessions are emergency data sessions. This information may be in the form of an indication sent from the MME to the MSC.

At 426, MSC 404 sends a message to l-CSCF. In some examples, the message comprises a DT-INVITE message. The message comprises a header-field. In some examples the header field comprises a predetermined entry. The predetermined entry may be a namespace. In some examples, the header field is a Resource-Priority header field comprising a namespace of“esnet”.

The message sent at 426 may also comprise a request universal resource identifier (RURI). In some examples the RURI may comprise an emergency session transfer number for single radio voice call continuity value (ESTNSR) for emergency calls. In some examples the l-CSCF uses the ESTNSR present in RURI to obtain EATF address. In some examples the I- CSCF gets the address from FISS in LIA message. At 428, l-CSCF 406 receives the message with the predetermined entry. l-CSCF 406 checks whether the message comprises the

predetermined entry. If the message comprises the predetermined entry, I- CSCF 406 determines that the data session is an emergency data session. In the case that the data session is an emergency data session, l-CSCF 406 handles the data session with a higher priority than other non-emergency data sessions.

When l-CSCF 406 handles the emergency data session with a higher priority than other data sessions, this may mean that even during overload situations l-CSCF 406 maintains the emergency data session. l-CSCF 406 may not maintain other lower priority data sessions. Maintaining a data session may comprise not dropping and/or not rejecting the data session. Maintaining a data session may comprise not dropping any packets of the data session.

At 428, after l-CSCF 406 has determined that the data session is an emergency data session, l-CSCF 406 sends a message to FISS 408. The message may comprise an indication that the data session that is set up at 412 (or is in the process of being set up) is an emergency data session. The message may comprise a location information request (LIR) message.

In some examples the l-CSCF carries out LIR to obtain information of the server which is handling the session for the UE. In a normal VOLTE call the server comprises an S-CSCF, whereas for an emergency call the server may comprise an EATF. According to some examples the l-CSCF does not know whether the identified server is an S-CSCF (e.g. in case of VOLTE) or an EATF (in case of emergency call) - whatever server name or identity the I- CSCF receives it simply forwards it. Another implementation can be that I- CSCF will check for RURI value in a preconfigured table, and if it matches, it can forward the value. In such a case LIR/LIA is not required as l-CSCF has obtained the server address from the table and already forwarded it.

Therefore in this example the LIR message is used for obtaining an identity of EATF that is serving UE 402. So that FISS 408 can handle the data session as high priority, l-CSCF 406 may include information in the message sent to FISS 408 that the data session comprises an emergency data session that should be handled with high priority.

The information that is comprised in the message sent from l-CSCF 406 to FISS 408 and is used by the FISS to determine that the data session is an emergency data session may be a value in the message. For example, the value may be“PRIORITY-0”. This value may be a Session-Priority attribute value pair (AVP).

At 432, following receiving the message comprising information that the data session is an emergency data session at 430, FISS 408 handles the data session with higher priority than other, non-emergency data sessions. When FISS 408 handles the emergency data session with a higher priority than other data sessions, this may mean that even during overload situations FISS 408 maintains the emergency data session. FISS 408 may not maintain other lower priority data sessions. Maintaining a data session may comprise not dropping and/or rejecting the data session. Maintaining a data session may comprise not dropping any packets of the data session.

At 434, FISS 408 provides a location information answer (LIA) message to l-CSCF 406 in response to the message sent at 432. The LIA message may include information regarding an EATF of UE 402. At 436, l-CSCF 406 can then send an invite message to EATF 424 in order to complete the handover at 438 of UE 402 from an LTE domain to a CS domain, wherein UE 402 is involved in an active or alerting emergency data session.

Figure 5 shows a further example of message flow between elements of a network. These elements include UE 502, MSC 504, l-CSCF 506, EATF 524 and PSAP 526. The person skilled in the art will understand that the network may comprise further elements that are not shown in Figure 5.

Steps 512 and 514 of Figure 5 are similar to steps 412 and 414 of Figure 4. Similarly to the method described in Figure 4, MSC 504 may be aware (i.e. have information) of which data sessions are emergency data sessions. For example, MSC 504 may receive this information from an MME regarding which data sessions are emergency data sessions. This

information may be in the form of an indication sent from the MME to the MSC. At 540, MSC 504 sends a message to l-CSCF 508. The message may be an invite message. The message may comprise a value, which in some examples may be an ESTNSR value. The message may be a domain transfer invite (DT-INVITE) message. The message may comprise a value. The message may comprise a RURI comprising an ESTNSR value for emergency calls. In some examples the l-CSCF uses the ESTNSR present in RURI to obtain EATF address. In some examples the l-CSCF gets the address from FISS in LIA message.

At 542 l-CSCF 506 compares the received value with a preconfigured list of values. In some examples, this comprises 542 l-CSCF comparing a received ESTNSR value with a preconfigured list of ESTNSR values. When the value matches a value in the list of values, the l-CSCF determines that the data session is an emergency data session.

The preconfigured list of values can be stored in a memory of l-CSCF 506. The preconfigured list of values may be ESTNSR values used by an operator for emergency data sessions. The preconfigured list of values may be updated with ESTNSR values used by an operator for emergency data sessions as these values are updated (i.e. the preconfigured list of values may be synchronized at l-CSCF 506 according to an operator’s emergency address policy). If l-CSCF 506 determines that the data session is an emergency data session, it may handle the data session with higher priority than other data sessions. This may mean that even during overload situations l-CSCF 406 maintains the emergency data session. l-CSCF 406 may not maintain other lower priority data sessions. Maintaining a data session may comprise not dropping and/or not rejecting the data session. Maintaining a data session may comprise not dropping any packets of the data session.

At 544 l-CSCF 506 uses ESTNSR value to determine an EATF address. In some examples, at least one ESTNSR value stored at l-CSCF 506 is equivalent to at one respective EATF address. In this case l-CSCF 506 can forward the data session to the respective EATF address equivalent to the ESTNSR value at 544.

At 546, the handover of UE 502 from an LTE domain to a CS domain is completed, wherein UE 502 is involved in an active or alerting emergency data session.

Figure 6 shows an example apparatus 650 in which embodiments of the invention may be applied. Apparatus 650 may be an element of the system shown in Figure 1. In some example embodiments, the apparatus 650 may, be embodied as, or included as a component of, a communications device with wired or wireless communications capabilities. The example apparatus may include or otherwise be in communication with one or more processors 652, memory devices 654, Input/Output (I/O) interfaces 656, communications interfaces 658 and/or user interfaces 660 (in Figure 6, one of each is shown as an example). Depending on the component of FIG. 1 being implemented by the apparatus, however, the apparatus may include additional elements and/or may not include one or more of the foregoing elements, such as the user interfaces.

Apparatus 650 may be a control apparatus, for example an l-CSCF or an MSC. The processor 652 may be embodied as various means for

implementing the various functionalities of example embodiments of the present invention including, for example, one or more of a microprocessor, a coprocessor, a controller, a special-purpose integrated circuit such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), DSP (digital signal processor), or a hardware accelerator, processing circuitry or other similar hardware. According to one example embodiment, the processor may be representative of a plurality of processors, or one or more multi-core processors, operating individually or in concert.

Whether configured as hardware alone or via instructions stored on a computer- readable storage medium, or by a combination thereof, the processor 652 may be an apparatus configured to perform operations according to embodiments of the present invention while configured

accordingly. Thus, in example embodiments where the processor is embodied as, or is part of, an ASIC, FPGA, or the like, the processor is specifically configured hardware for conducting the operations described herein.

Alternatively, in examples where the processor is an executor of instructions stored on a computer-readable storage medium, the instructions specifically configure the processor to perform the algorithms and operations described herein. In some example embodiments, the processor is a processor of a specific device configured for employing example embodiments of the present invention by further configuration of the processor via executed instructions for performing the algorithms, methods, and operations described herein.

The memory device 654 may be one or more computer-readable storage media that may include volatile and/or non-volatile memory. In some example embodiments, the memory device may include Random Access Memory (RAM) including dynamic and/or static RAM, on-chip or off-chip cache memory, and/or the like. Further, the memory device may include non- volatile memory, which may be embedded and/or removable, and may include, for example, Read-Only Memory (ROM), flash memory, magnetic storage devices (for example, hard disks, floppy disk drives, magnetic tape, etc.), optical disc drives and/or media, non-volatile random access memory (NVRAM), and/or the like. The memory device may include a cache area for temporary storage of data. In this regard, at least a portion or the entire memory device may be included within the processor 652.

Further, the memory device 654 may be configured to store

information, data, applications, computer-readable program code instructions, and/or the like for enabling the processor 652 and the example apparatus 650 to carry out various functions in accordance with example embodiments of the present invention described herein. For example, the memory device may be configured to buffer input data for processing by the processor. Additionally, or alternatively, the memory device may be configured to store instructions for execution by the processor. The memory may be securely protected, with the integrity of the data stored therein being ensured. In this regard, data access may be checked with authentication and authorized based on access control policies.

The I/O interface 656 may be any device, circuitry, or means embodied in hardware, software or a combination of hardware and software that is configured to interface the processor 652 with other circuitry or devices, such as the communications interface 658 and/or the user interface 660. In some example embodiments, the processor may interface with the memory device via the I/O interface. The I/O interface may be configured to convert signals and data into a form that may be interpreted by the processor. The I/O interface may also perform buffering of inputs and outputs to support the operation of the processor. According to some example embodiments, the processor and the I/O interface may be combined onto a single chip or integrated circuit configured to perform, or cause the apparatus 200 to perform, various functionalities of an example embodiment of the present invention. The communication interface 658 may be any device or means embodied in hardware, software or a combination of hardware and software that is configured to receive and/or transmit data from/to one or more networks 664 and/or any other device or module in communication with the example apparatus 650. The processor 202 may also be configured to facilitate communications via the communications interface by, for example, controlling hardware included within the communications interface. In this regard, the communication interface may include, for example, one or more antennas, a transmitter, a receiver, a transceiver and/or supporting hardware, including, for example, a processor for enabling communications. Via the communication interface, the example apparatus may communicate with various other network elements in a device-to-device fashion and/or via indirect communications.

The communications interface 658 may be configured to provide for communications in accordance with any of a number of wired or wireless communication standards. The communications interface may be configured to support communications in multiple antenna environments, such as multiple input multiple output (Ml MO) environments. Further, the communications interface may be configured to support orthogonal frequency division multiplexed (OFDM) signaling. In some example embodiments, the

communications interface may be configured to communicate in accordance with various techniques including, as explained above, any of a number of second generation (2G), third generation (3G), fourth generation (4G) or higher generation mobile communication technologies, radio frequency (RF), or any of a number of different wireless networking techniques. The

communications interface may also be configured to support communications at the network layer, possibly via Internet Protocol (IP). The user interface 660 may be in communication with the processor 652 to receive user input from a user 662 via the user interface and/or to present output to a user as, for example, audible, visual, mechanical or other output indications. The user interface may include, for example, a keyboard, a mouse, a joystick, a display (for example, a touch screen display), a microphone, a speaker, or other input/output mechanisms. Further, the processor may comprise, or be in communication with, user interface circuitry configured to control at least some functions of one or more elements of the user interface. The processor and/or user interface circuitry may be configured to control one or more functions of one or more elements of the user interface through computer program instructions (for example, software and/or firmware) stored on a memory accessible to the processor (for example, the memory device 654). In some example embodiments, the user interface circuitry is configured to facilitate user control of at least some functions of the apparatus 650 through the use of a display and configured to respond to user inputs. The processor may also comprise, or be in communication with, display circuitry configured to display at least a portion of a user interface, the display and the display circuitry configured to facilitate user control of at least some functions of the apparatus. In some cases, the apparatus 650 may be implemented in a chip or chip set. In an example embodiment, the chip or chip set may be programmed to perform one or more operations of one or more methods as described herein and may include, for instance, one or more processors 652, memory devices 654, I/O interfaces 656 and/or other circuitry components

incorporated in one or more physical packages (for example, chips). By way of example, a physical package may include an arrangement of one or more materials, components, and/or wires on a structural assembly (for example, a baseboard) to provide one or more characteristics such as physical strength, conservation of size, and/or limitation of electrical interaction. It is

contemplated that in certain embodiments the chip or chip set can be implemented in a single chip. It is further contemplated that in certain embodiments the chip or chip set can be implemented as a single "system on a chip." It is further contemplated that in certain embodiments a separate ASIC may not be used, for example, and that all relevant operations as disclosed herein may be performed by a processor or processors. A chip or chip set, or a portion thereof, may constitute a means for performing one or more operations of one or more methods as described herein.

Figure 7 is a flow chart of a method according to an example. The method of Figure 7 may be carried out at an apparatus. For example the apparatus may comprise an l-CSCF. At S1 , the method comprises receiving a first message at the apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication.

At S2 the method comprises determining, at the apparatus and based at least in part on the indication, that the data session comprises an

emergency data session.

Figure 8 is a flow chart of a method according to an example. The method of Figure 8 may be carried out at an apparatus. For example the apparatus may comprise an MSC. At S1 , the method comprises sending a message from the apparatus to a further apparatus during a handover of a data session from a first network to a second network. The message comprises an indication that the data session comprises an emergency data session.

In general, the various examples shown may be implemented in hardware or in special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

Some embodiments may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware.

Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus- readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out methods are described in the present disclosure. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media. The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples. Examples of the disclosed embodiments may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a

semiconductor circuit design ready to be etched and formed on a

semiconductor substrate. The examples described herein are to be understood as illustrative examples of embodiments of the invention. Further embodiments and examples are envisaged. Any feature described in relation to any one example or embodiment may be used alone or in combination with other features. In addition, any feature described in relation to any one example or embodiment may also be used in combination with one or more features of any other of the examples or embodiments, or any combination of any other of the examples or embodiments. Furthermore, equivalents and modifications not described herein may also be employed within the scope of the invention, which is defined in the claims.

Claims

1. An apparatus comprising means for performing:

receiving a first message at the apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication;

determining, at the apparatus and based at least in part on the indication, that the data session comprises an emergency data session.

2. An apparatus according to claim 1 wherein the means are further configured to perform: giving priority to the emergency data session over other data sessions.

3. An apparatus according to claim 2, wherein the apparatus is configured such that the giving priority to the emergency data session over other data sessions comprises maintaining the emergency data session in a situation where the apparatus is overloaded.

4. An apparatus according to any preceding claim, wherein the indication is comprised in a header field of the message.

5. An apparatus according to claim 4, wherein the means are further configured to perform: determining that the data session is an emergency data session when the header field comprises a predetermined entry.

6. An apparatus according to claim 5 wherein the means are further configured to perform: sending a second message to a home subscriber server in response to the receiving a first message, the second message comprising a location information request message, wherein the second message comprises information indicating that the second message is a high priority message.

7. An apparatus according to any of claims 1 to 3 wherein the indication comprises a value.

8. An apparatus according to claim 7 wherein the means are further configured to perform: comparing, at the apparatus, the value with a list of values stored at the apparatus; wherein when the value of the indication matches a value in the list the apparatus determines that the data session is an emergency data session.

9. An apparatus according to claim 8 wherein the means are further configured to perform: forwarding the emergency data session from the apparatus to an address corresponding to the value.

10. An apparatus according to any preceding claim wherein the apparatus comprises an interrogating call session control function.

11. An apparatus according to any preceding claim wherein the first network is a long-term evolution network and the second network is a circuit switched network.

12. An apparatus comprising means for performing:

13. An apparatus according to claim 12, wherein the indication is comprised in a header field of the message.

14. An apparatus according to claim 13, wherein the indication comprises a predetermined entry comprised in the header field.

15. An apparatus according to claim 12 or claim 13 wherein the indication comprises a value.

16. An apparatus according to any of claims 12 to 15, wherein the means are further configured to perform: receiving information that the data session is an emergency data session from a mobile management entity.

17. An apparatus according to any preceding claim, wherein the apparatus comprises a mobile switching centre.

18. An apparatus according to any preceding claim wherein the first network is long-term evolution network and the second network is a circuit switched network.

19. The apparatus of any preceding claim wherein the means comprises: at least one processor; and

at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

20. A method comprising:

receiving a first message at an apparatus during a handover of a data session from a first network to a second network, the first message comprising an indication;

21. A method according to claim 20, wherein the method comprises giving priority to the emergency data session over other data sessions.

22. A method according to claim 21 , wherein the giving priority to the emergency data session over other data sessions comprises maintaining the emergency data session in a situation where the apparatus is overloaded.

23. A method according to any of claims 20 to 22, wherein the indication is comprised in a header field of the message.

24. A method according to any of claims 20 to 22, wherein the indication comprises a value, and the method comprises comparing, at the apparatus, the value with a list of values stored at the apparatus; wherein when the value of the indication matches a value in the list the apparatus determines that the data session is an emergency data session.

25. A computer program comprising instructions for causing an apparatus to perform at least the following:

26. A method comprising:

sending a message from an apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.

27. A method according to claim 26, wherein the indication is comprised in a header field of the message.

28. A method according to claim 26 or claim 27, wherein the indication comprises a predetermined entry comprised in the header field.

29. A method according to claim 26, wherein the indication comprises a value.

30. A computer program comprising instructions for causing an apparatus to perform at least the following:

sending a message from the apparatus to a further apparatus during a handover of a data session from a first network to a second network, the message comprising an indication that the data session comprises an emergency data session.