BACKGROUND

[0001] The present invention relates a method for an improved handling of an IMS (Internet Multimedia Subsystem) conversational service of a user equipment being connected to a telecommunications network comprising or being associated to an IMS network, wherein the user equipment applies a request timer information, related to a request timeout time interval, when attempting to initiate the IMS conversational service.

[0002] Furthermore, the present invention relates to a system for improved handling of an IMS conversational service of a user equipment being connected to a

telecommunications network, the system comprising the telecommunications network and the user equipment, wherein the user equipment applies a request timer information by means of attempting to initiate the IMS conversational service while a request timeout time interval, relating to the request timer information, has not expired. [0003] Additionally, the present invention relates to telecommunications network and to a user equipment, both being part of the inventive system, and to a program and a computer program product causing to perform an inventive method.

[0004] In known implementations of telecommunications networks, especially in mobile communication networks, IMS services involving the use of SIP (Session Initiation Protocol) functionalities typically apply SIP related timers such as specified in 3GPP TS 24.229 (Rel.13 version 13.5.1 ) clause 7.7, which are used for SIP session and SIP transaction timeout control. This typically means, e.g. for the so-called B timer, that this timer (i.e. the time interval related to that timer) is 64 times another timer (called T1 ) which is defined to correspond to 2 seconds (i.e. the time interval corresponding to the T1 timer is set to be 2 seconds for the user equipment), which means effectively, that the so- called B timer (i.e. the related time interval) corresponds to 128 seconds. As in conventional implementations this B timer is typically used for SIP session and SIP transaction timeout control, this results in a session timeout of more than 2 minutes which, for conversational services, does typically not correspond to an acceptable user experience. However, as every telecommunications network is different (due to different network architecture, different network nodes and a different geographical redundancy), the request timeout time intervals to be applied should be adapted to the specific situation considered.

SUMMARY

[0005] An object of the present invention is to provide an effective and simple solution to apply session timeout timers that are as much as possible adapted to the telecommunications network (or the plurality of telecommunications networks involved - e.g. of the caller and the callee) used and/or adapted to the situation of the user of that telecommunications network, in order to both enhance the user experience, the ease of use for providing communication services to the user, and especially a faster

establishment of communication links or communication sessions, as well as avoid unnecessary network load.

[0006] The object of the present invention is achieved by a method for improved handling of an IMS (Internet Multimedia Subsystem) conversational service of a user equipment being connected to a telecommunications network comprising or being associated to an IMS network,

wherein the user equipment applies a request timer information, related to a request timeout time interval, when attempting to initiate the IMS conversational service, wherein the request timeout time interval is started upon the initiation of the IMS conversational service, wherein the method comprises the following steps:

— in a first step, the user equipment attempts to SIP (Session Initiation Protocol) register towards the telecommunications network or the IMS network,

— in a second step, subsequent to the first step, the user equipment attempts to initiate the IMS conversational service, and

wherein the request timer information, related to the request timeout time interval to be applied by the user equipment for the IMS conversational service, is transmitted, by the telecommunications network, to the user equipment either during the first step and/or during the second step, wherein the IMS conversational service is attempted to be initiated while the request timeout time interval has not expired.

[0007] According to the present invention, the request timer information is transmitted to the user equipment in connection to the communication session during which the IMS conversational service is requested. It is thereby advantageously possible according to the present invention to help to improve customer satisfaction and user experience of a user of the inventive telecommunications network by means of having these timers (i.e. the request timeout time interval corresponding to the request timer information) configured in a manner suitable to the specific current communication situation of the user equipment.

[0008] By means of transmitting the request timer information - related to the request timeout time interval (to be applied by the user equipment for the IMS

conversational service, is transmitted) -, by the telecommunications network, to the user equipment either during the first step (during which the user equipment attempts to SIP (Session Initiation Protocol) register towards the telecommunications network or the IMS network) and/or during the second step (during which the user equipment attempts to initiate the IMS conversational service), it is advantageously possible according to the present invention that a context information is available to the telecommunications network (relating to the context or the situation of the user equipment currently transmitting the request) such that the request timer information can be transmitted to the user equipment that is most suited to the current context or situation of the user equipment.

[0009] As every telecommunications network is different, when configuring the telecommunications network, it is required to define different timers (i.e. time intervals) to be applied by the different network nodes as well as by the user equipments involved, in order to deal with time delays related to the network nodes of the telecommunications network and/or related to the distances between the network nodes. Hence, providing the possibility according to the present invention, to define or configure the request timeout timers or request timeout time intervals by means of being able to transmit the corresponding request timer information as best suited to the situation or context of the user equipment, it is advantageously possible to give the possibility (to the network operator of the telecommunications network) to alter the behavior of the user equipments according to the specific current situation of the telecommunications network involved. This allows to adapt the behavior, i.e. the responses, of the individual user equipments within the telecommunications network more appropriately in view of the network architecture specifics (especially regarding data transport and transport redundancy) of the telecommunications network considered; e.g. in some situations (or parts of the telecommunications network) a longer time for a response of the SIP request (i.e. the SIP registration request or the SIP invite request of the user equipment) - hence the corresponding request timeout time interval to be applied in that telecommunications network should be set to a longer time interval, thereby only slightly reducing user experience but avoiding excessively high rates of aborted or unsuccessful SIP requests - could be appropriate, whereas in other situations (or parts of the telecommunications network) shorter times (hence providing the possibility to set the corresponding request timeout time interval to be applied in that (different) telecommunications network to a shorter time interval, thereby improving user experience) could be feasible.

[0010] Furthermore according to an advantageous embodiment of the present invention, - during the first step - the user equipment attempts to SIP register towards the telecommunications network or the IMS network by transmitting a SIP register message to a network node of the IMS network of the telecommunications network.

[0011] By means of transmitting the request timer information during the first step, it is advantageously possible that the user equipment already knows the request timeout time interval to apply (when actually initiating the IMS conversational service) while performing the registration step (i.e. sometime "long" before actually initiating the conversational service (e.g. placing a call) by means of transmitting the SIP invite message.

[0012] Furthermore according to an advantageous embodiment of the present invention, - during the second step - the request timeout time interval is started upon the user equipment transmitting or attempting to transmit - in view of initiating the IMS conversational service - a SIP invite message to a network node of the IMS network of the telecommunications network.

[0013] By means of transmitting the request timer information during the second step, it is advantageously possible that the telecommunications network very precisely knows the situation of the user equipment, and is, thus, able to provide (and transmit) the request timer information accordingly such that the request timeout time interval to apply is best suited to that situation.

[0014] According to a further embodiment of the present invention, it is

advantageously possible that the request timeout time interval related to the request timer information is dependent on at least one out of the following:

— the radio access of the user equipment towards the telecommunications network when attempting to initiate the IMS conversational service,

— the kind of radio service requested by the user equipment,

— the kind of IMS conversational service,

— the kind of interconnection scenario of the user equipment towards the telecommunications network,

— the capabilities of the user equipment.

[0015] By means of adjusting the request timeout time interval dependent on different parameters, it is advantageously possible to adapt the request timer information (and hence the request timeout time interval to apply) in the most suitable manner.

[0016] According to a further embodiment of the present invention, it is also advantageously possible that the IMS conversational service corresponds to a voice call service or to a video call service or to a push-to-talk service or to an emergency call service. [0017] Furthermore, the present invention relates to a system for improved handling of an IMS (Internet Multimedia Subsystem) conversational service of a user equipment being connected to a telecommunications network, wherein the system comprises the telecommunications network and the user equipment, wherein the telecommunications network comprises or is associated to an IMS network, wherein the user equipment applies a request timeout time interval, related to a request timer information, when attempting to initiate the IMS conversational service, wherein the request timeout time interval is started upon the initiation of the IMS conversational service, wherein the system is configured such that:

— the user equipment attempts to SIP (Session Initiation Protocol) register towards the telecommunications network or the IMS network,

— the user equipment then attempts to initiate the IMS conversational service, wherein the request timer information, related to the request timeout time interval to be applied by the user equipment for the IMS conversational service is transmitted, by the telecommunications network, to the user equipment either during the first step or during the second step, wherein the IMS conversational service is attempted to be initiated while the request timeout time interval has not expired.

[0018] Thereby, it is advantageously possible to provide a system such that customer satisfaction and user experience of a user of the inventive telecommunications network is improved by means of having timeout timers (i.e. the request timeout time interval corresponding to the request timer information) configurable by the network operator, especially for each device or user equipment used in the telecommunications network and for each event of an initiation of an IMS conversational service by a user equipment. [0019] Advantageously, it is especially possible according to the present invention, that the system is furthermore configured such that the request timeout time interval is started upon the user equipment transmitting or attempting to transmit - in view of initiating the IMS conversational service - a SIP invite message to a network node of the IMS network of the telecommunications network.

[0020] Furthermore advantageously, the request timeout time interval related to the request timer information is dependent on at least one out of the following:

— the radio access of the user equipment towards the telecommunications network when attempting to initiate the IMS conversational service,

— the kind of radio service requested by the user equipment,

— the kind of IMS conversational service,

— the kind of interconnection scenario of the user equipment towards the

telecommunications network,

— the capabilities of the user equipment. [0021] Furthermore, the present invention relates to a telecommunications network for improved handling of an IMS (Internet Multimedia Subsystem) conversational service of a user equipment, the telecommunications network being part of an inventive system.

[0022] Furthermore, the present invention relates to a user equipment for improved handling of an IMS (Internet Multimedia Subsystem) conversational service to a telecommunications network, the user equipment being part of an inventive system.

[0023] Additionally, the present invention relates to a program comprising a computer readable program code which, when executed on a computer or on a network node of a telecommunications network or on a user equipment or in part on the network node of a telecommunications network and in part on the user equipment, causes the computer or the network node of the telecommunications network or the user equipment to perform the inventive method.

[0024] Still additionally, the present invention relates to a computer program product for improved handling of an IMS (Internet Multimedia Subsystem) conversational service of a user equipment being connected to a telecommunications network comprising or being associated to an IMS network, the computer program product comprising a computer program stored on a storage medium, the computer program comprising program code which, when executed a computer or on a network node of a

telecommunications network or on a user equipment or in part on the network node of a telecommunications network and in part on the user equipment, causes the computer or the network node of the telecommunications network or the user equipment to perform the inventive method.

[0025] These and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 schematically illustrate a mobile communication network as an example of an inventive telecommunications network, comprising or being associated to an IMS network.

[0027] Figure 2 schematically illustrates a communication diagram related to the inventive method.

DETAILED DESCRIPTION

[0028] The present invention will be described with respect to particular

embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non- limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

[0029] Where an indefinite or definite article is used when referring to a singular noun, e.g. "a", "an", "the", this includes a plural of that noun unless something else is specifically stated.

[0030] Furthermore, the terms first, second, third and the like in the description and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0031] In Figure 1 , a mobile communication network 100 as an example of an inventive telecommunications network 100 is schematically shown. The

telecommunications network 100 comprises or is associated to an IMS network 150. In the exemplary embodiment of Figure 1 , the telecommunications network 100 is realized as a cellular mobile communication network 100, comprising an access network 1 10 and a core network 120. Furthermore in the exemplary embodiment of Figure 1 , the access network 1 10 comprises a first radio cell 1 1 and a second radio cell 12. A first base station entity 1 1 1 serves the first radio cell 1 1 , and a second base station entity 1 12 serves the second radio cell 12. Of course, typically, a mobile communication network comprises a certain number of radio cells, typically far exceeding two radio cells. Instead of realizing the telecommunications network 100 as a mobile communication network 100, it is also possible according to the present invention (but not shown in Figure 1 ) that the telecommunications network 100 is realized as a fixed line telecommunications network 100. Also in the latter case, the telecommunications network 100 typically comprises an access network (not shown) and a core network similar to the core network 120 of the mobile communication network 100 as schematically shown in Figure 1.

[0032] The telecommunications network 100 comprises, especially as part of its core network 120, or, at least, accessible by the core network 120 of the telecommunications network 100, an IMS network 150. The IMS network 150 typically comprises a plurality of network nodes, one of which being designated by reference sign 151 in Figure 1.

[0033] Furthermore, the telecommunications network 100 typically comprises (or is associated with) a plurality of user equipments, one of which is designated in Figure 1 by reference sign 20, a further user equipment is designated by reference sign 21

(alternatively, one could speak of the first user equipment 20 and a further or second user equipment 21 ).

[0034] According to the present invention, an improved method of handling an IMS (Internet Multimedia Subsystem) conversational service is proposed. The method assumes that a user equipment 20 is connected to the telecommunications network 100 that comprises (or is associated) to the IMS network 150 (comprising (at least) the (IMS) network node 151 ). This is schematically shown by means of the communication diagram of Figure 2, schematically showing the communication between the user equipment 20, the telecommunications network 100, and the IMS network 150/network node 151. [0035] According to the present invention, it is assumed that - in a first step - the user equipment 20 attempts to SIP (Session Initiation Protocol) register towards the telecommunications network 100 or the IMS network 150 which is represented in Figure 2 by means of an arrow from the user equipment 20 towards the IMS network 150/the IMS network node 151 (that could also be represented by an analogous arrow from the user equipment 20 to the telecommunications network 100) and reference sign 210. According to a first alternative according to the present invention, as at least one result of the SIP register message 210 (or SIP registration message 210), the IMS network 150/the IMS network node 151 transmits the request timer information 25 to the user equipment 20 (or the telecommunications network 100 transmits the request timer information 25 to the user equipment 20); this is represented in Figure 2 by means of reference sign 25 being encircled by a dashed line. The first step, hence the SIP registration of the user equipment 20, can occur either directly prior to the second step (which corresponds to the user equipment 20 transmitting a SIP invite message 220 to the IMS network 150/the IMS network node 151 or to the telecommunications network 100), or it can occur a considerable time (or many minutes or even many hours if not many days) prior to the second step.

[0036] According to the present invention, it is furthermore assumed that - in the second step - the user equipment 20 attempts to transmit a SIP (Session Initiation Protocol) invite message 220 towards the telecommunications network 100 or the IMS network 150 which is represented in Figure 2 by means of an arrow from the user equipment 20 towards the IMS network 150/the IMS network node 151 (that could also be represented by an analogous arrow from the user equipment 20 to the

telecommunications network 100) and reference sign 220. According to a second alternative according to the present invention, as at least one result of the SIP invite message 220, the IMS network 150/the IMS network node 151 transmits the request timer information 25 to the user equipment 20 (or the telecommunications network 100 transmits the request timer information 25 to the user equipment 20); this is represented in Figure 2 by means of reference sign 25 being encircled by a drawn-through line. [0037] According to the present invention, the request timer information 25, related to the request timeout time interval 250 to be applied by the user equipment 20 for the IMS conversational service, is transmitted, by the telecommunications network 100, to the user equipment 20 either during the first step (hence, according to the first alternative, only the request timer information 25 encircled by a dashed line as in Figure 2 is considered) or during the second step (hence, according to the second alternative, only the request timer information 25 encircled by a drawn-through line as in Figure 2 is considered); subsequently, the IMS conversational service is attempted to be initiated while the request timeout time interval 250 has not expired. According to a further embodiment of the present invention, the (identical) request timer information 25 is both transmitted during the first step and during the second step (i.e. both the request timer 5 information 25 encircled by the dashed line and the one encircled by the drawn-through line are considered).

[0038] Once the request timer information 25 (corresponding to the request timeout time interval 250) is transmitted to the user equipment 20, the request timer information 25 is applied by the user equipment 20 while the user equipment 20 attempts to initiate

10 the IMS conversational service, by means of sending the SIP invite message 220 to the network node 151 of the IMS network 150 (or to the telecommunications network 100; which is not shown). This applying the request timeout time interval 250 is represented, in Figure 2, by a rectangle, having drawn-through lines, comprising the SIP invite message 220 from the user equipment 20 to the network node 151 of the IMS network 150. After

15 sending the SIP invite message 220, the request timeout time interval 250 is started

(indicated by a vertical arrow on the left hand side of the rectangle representing the user equipment 20 attempting to initiate the IMS conversational service. Figure 2 exemplarily shows the situation of the attempt (of the user equipment 20) failing, being indicated by a crossed out return arrow being directed from the IMS network 150/network node 151

20 towards the user equipment 20. The attempt is aborted when the request timeout time interval 250 expires.

[0039] In both cases described above, the error situation (why the attempt of the user equipment 20 to initiate the IMS conversational service by means of the SIP invite message 210 fails) typically includes that there is no answer (to the SIP invite message 25 210) received in the user equipment 20, e.g. due to:

— lack of coverage in LTE (Long Term Evolution) domain,

— the P-CSCF (Proxy Call Serving Control Function) to which the UE is registered being down (e.g. due to hardware or power failure), transport layer to P-CSCF is down (router failure),

30 — the transport layer to the P-CSCF being down (e.g. due to a router failure),

— the physical (transport) layer to the P-CSCF being down (e.g. due to a problem in transmission).