The present invention relates to a method for invoking a service in a telecommunications network comprising a switching node and an intelligent network, the intelligent network comprising a service control entity and a service switching entity, wherein the switching node receives a request to set up a call, determines if the call requires invocation of a service in the intelligent network, and if so, instructs the service switching entity, and proceeds set up of the call. The switching node is e.g. a mobile switching center (MSC) in a mobile telecommunications network, and the service switching entity is e.g. a service switch function (SSF). The service control entity may be a service control point (SCP), known as such in mobile telecommunications networks. Furthermore, the present invention relates to methods for invoking a service in a telecommunications network relating to specific functionalities of the service switching entity, the service control entity, or a combination of the switching node, service switching entity, and the service control entity.
In a further aspect, the present invention relates to a switching node in a telecommunication, a service switching entity in an intelligent network or a service control entity in an intelligent network.
This method may be applied in mobile communication networks, in which case the exchange or switching node, which is a basic entity in a network for establishing connections between network terminals, is a mobile switching center (MSC). Determining whether the call to be initiated further requires initiation of a service (e.g. an Intelligent Network (IN) service), is e.g. implemented by analyzing various call related parameters.
Normally, the initiation of a service entails that call set up by the exchange is suspended, until the initiation of the service is reported back to the exchange and the service has given further instruction. This is e.g. described in GSM specifications TS03.78 and TS09.78 for a GSM communication network as is known to the person skilled in the art. In various applications, e.g. when call establishment is critical, such a suspension or waiting period in the call set up is not desired.
The present invention seeks to provide a solution wherein disadvantageous effects of such a suspension or waiting period are minimized.
According to the present invention, a method according to the preamble defined above is provided, in which proceeding set up of the call is executed before an instruction from the service switching entity is received. This allows to minimize the waiting period and directly proceed with the call set up (independent from the service invocation).
In a further embodiment, determining if the call requires invocation of a service in the intelligent network comprises checking whether there is a trigger detection point in notify mode (TDP-N) applicable for the call. Using a TDP in notify mode allows to continue call set up immediately without delay, as in conventional methods where in such a case a trigger detection point in report mode (TDP-R) is used.
Instructing the service switching entity comprises in a further embodiment sending an indication that the set up of the call is not suspended. This allows to maintain the relation between the switching node and the service switching entity.
A further embodiment relates to the situation where a service needs to be invoked during an existing call. In this embodiment, the method further comprises receiving a notification that a first state model in the switching node having a plurality of detection points associated with the call has made a transition to a detection point, determining if the transition is to be reported to the service switching entity and if so, reporting the transition and continuing the call before an instruction from the service switching entity is received. With this embodiment, it is also possible to invoke a service in a more efficient manner during an existing call.
Furthermore, the present invention relates to specific functionality of the service switching entity, i.e. a method for invoking a service in a telecommunications network comprising a switching node and an intelligent network, the intelligent network comprising a service control entity and a service switching entity, wherein the service switching entity receives an instruction from the switching node, selects a predefined set of detection points in accordance with the received instruction, sends a message to the service control entity, receives a response from the service control entity, and arms the detection points from the selected predefined set. The instruction comprises an indication that the call set up is not suspended in a further embodiment. The message is e.g. an Initial Detection Point (IDP) message comprising an information element indicating the predefined set of detection points and comprising an indication that the call set up is not suspended.
In a further embodiment, the method further comprises receiving a report that a first state model in the switching node having a plurality of detection points associated with the call has made a transition to a detection point, selecting a predefined set of detection points in accordance with the received notification, determining if the transition is to be reported to the service control entity, and if so, sending a message comprising an indication of the transition and comprising an information element indicating the predefined set of detection points to the service control entity, and arming the detection points from the selected predefined set.
Also, the present invention relates to specific functionality of the service control entity, i.e. a method for invoking a service in a telecommunications network comprising a switching node and an intelligent network, the intelligent network comprising a service control entity and a service switching entity, wherein the service control entity receives a message from the service switching entity comprising an information element indicating a predefined set of detection points to be armed by the service switching entity, invokes the service, aligns a second state model in the invoked service in accordance with the predefined set of detection points, and sends a response to the service switching entity (acknowledging the IDP).
According to an embodiment, the message from the service switching entity is an Initial Detection Point message. The message, in a further embodiment comprises an indication that the call set up is not suspended.
Furthermore, an embodiment of the present method further comprises receiving a message comprising a notification that a first state model in the switching node having a plurality of detection points associated with the call has made a transition to a detection point, and comprising an information element indicating a predefined set of detection points to be armed by the service switching entity, and aligning the second state model in the invoked service in accordance with the transition and with the predefined set of detection points.
The present invention is also embodied as the functionality of an ensemble of network nodes in a telecommunications network, i.e. a method for invoking a service in a telecommunications network comprising a switching node and an intelligent network, the intelligent network comprising a service control entity and a service switching entity, wherein the switching node receives a request to set up a call, determines if the call requires invocation of a service in the intelligent network, and if so, instructs the service switching entity and proceeds set up of the call before an instruction from the service switching entity is received, wherein the service switching entity further selects a predefined set of detection points in accordance with the received instruction, sends a message to the service control entity, receives a response from the service control entity, and arms the detection points from the selected predefined set, and wherein the service control entity further invokes the service, aligns a second state model in the invoked service in accordance with the predefined set of detection points and sends a response to the service switching entity. The method in a further embodiment comprises the combination of functionalities of the switching node, service switching entity and service control entity for the case when a service needs to be invoked during an existing call, as described in claim 14.
In a further aspect, the present invention relates to a switching node in a telecommunication network, a service switching entity, or a service control entity, which interact and are arranged to execute the method embodiments of the present invention.
In an even further aspect, the present invention relates to a computer program product comprising computer executable code, which when loaded on a computer system, allows the computer system to execute the method according to any one of the embodiments above.
The present invention will be discussed in more detail below, using a number of exemplary embodiments, with reference to the attached drawings, in which
The present invention may be applied in communication networks, e.g. a mobile telecommunication network. The relevant parts of such a telecommunication network are shown schematically in
The MSC 18, SSF 17 and the SCP 16 may be implemented as network units 1401, the structure of which is shown in simplified form in
In known methods of invoking or initiating an IN service, the MSC 18 (or SSF 17) notifies the SCP 16 (or SCF 19). However, when the SSF 17 has triggered the respective IN service, the SSF 17 will wait for further instructions from the IN service. The SSF 17 Finite State Machine (FSM) has made a transition to the state ‘Waiting for Instructions (WfI)’, and the call establishment process is now suspended. Call establishment continues only when the SSF 17 has received a ‘Continue’ (CUE) operation from the SCP 16 or SCF 19.
For cases where call establishment is critical, it may not be desirable to suspend the call establishment process. One example is the invocation of an IN service for emergency calls. Embodiments of the present invention are arranged to provide a method in which an IN service is invoked without suspending the call establishment process, in which the relationship between the IN service and the MSC 18 (or SSF 17) may be retained after service invocation, without explicit request from the IN service, and in which the IN service receives call establishment process notifications in accordance with existing IN mechanisms.
The method described below in accordance with a number of embodiments of the present invention entails that an SSF 17 can apply implicit arming of Detection Points (DP). Detection Points are a method used in the description of state models of present day telecommunication networks (called Basic Call State Model, BCSM). Detection Points represent predefined events in e.g. the establishment of a call in the telecommunication network. In accordance with existing IN methodology, an instance of a BCSM is invoked when the MSC 18 has deduced that a call shall be subject to IN control. The type of BCSM that is instantiated depends on the call case. For a Mobile Originating (MO) call for which a CAMEL Phase 2 service shall be invoked, an O-BCSM (Originating BCSM) is instantiated, as shown schematically in
The O-BCSM consists of various Detection Points (DP) and Points in Call (PiC), such as the indicated O_Active PiC. The basic call transitions are indicated by solid lines, and transitions beyond basic call are indicated by broken lines. Basic state model transitions are those transitions that follow from the structure of the BCSM. State model transitions beyond basic call are those transitions that are enforced by a service control entity.
In the normal situation, a CAMEL service is started as a result of the static arming of a DP as Trigger Detection Point (TDP) in “Request Mode” (TDP-R). For a CAMEL Phase 2 service for a mobile originated or mobile forwarded call, the DP that may be statically armed as TDP-R is DP Collected_Info (DP2).
The CAMEL service that is now started by the SCF 19, residing in the SCP 16, may arm additional DPs in the BCSM instance in the SSF 17. These DPs are in that case dynamically armed. A DP that is dynamically armed within a service instance is referred to as an EDP (Event Detection Point).
This leads to the following distinction:
TDP: A TDP is a DP that is statically armed in the MSC 18; the CAMEL service is triggered when the conditions that are associated to this TDP are fulfilled. According to CAMEL and Capability Set 1 (CS1) standards, a TDP is always “TDP-R”; that means that when the SSF 17 has initiated the service processing, the call processing in the MSC 18 is suspended and the SSF 17 waits for further instructions from the service (in the SCF 19).
EDP: An EDP is a DP that is dynamically armed by a service instance. The conditions for arming a DP are determined by the service (in the SCF 19), not by the SSF 17. A DP may be armed as EDP-N (Notify mode) or as EDP-R (Request mode). In the former case (EDP-N), the occurrence of the event is reported to the service and call handling in the MSC 18 continues. In the latter case (EDP-R), the occurrence of the event is reported to the service and call handling in the MSC 18 is suspended.
When an IN service requires further call process notifications, that service needs to be triggered by means of a TDP-R, enabling the service to arm subsequent service events. The effect of the service triggering by means of a TDP-R is that the call establishment process is suspended. As discussed earlier, suspending the call establishment process may not always be desirable.
The present invention presents two elements that offer a solution to the above-described dilemma (and which may be used as such or in combination):
Use of a TDP-N (Trigger Detection Point—Notify mode):
A TDP-N is a DP that is statically armed in the MSC 18. A distinctive aspect of a TDP-N, compared to TDP-R, is that the call establishment process is not suspended when the service is started.
Implicit arming of Detection Points:
Implicit arming of Detection Points entails that when the SSF 17 has invoked an IN service, it automatically arms designated DPs in the BCSM instance.
In the following, an exemplary embodiment will be described in more detail. When a call is established between an originating terminal 1 and a destination terminal 2, the MSC 18 may deduce from designated call related parameters that an IN service shall be invoked for this call. This deduction triggers the MSC 18 to hand over control of the call to the SSF 17. The SSF 17 determines which IN trigger data apply for this call. The IN trigger for this call contains a TDP-N definition. The SSF 17 prepares an Initial Detection Point (IDP) operation in accordance with existing IN specifications. The SSF 17 then sends the IDP to the SCP 16. The IDP is sent in a TCAP (Transaction Capabilities Application Part) TC_Begin message.
The SSF 17 applies the following two steps:
Implicit TDP disarming: Regular IN service triggering entails that when the IN service is triggered, the TDP-R that led to the service triggering remains armed until the service sends a call continuation operation, such as ‘Continue’ (CUE). When, however, an IN service is triggered with a TDP-N, as proposed by the present invention, then this TDP-N is implicitly disarmed upon its occurrence and reporting (see e.g. the TC_Begin[Initial DP] message in
Implicit EDP arming: In order to be able to report subsequent call events to the service, the SSF 17 applies implicit arming of DPs. That means that the service need not explicitly instruct the arming of these events (which is normally done by a Request Report BCSM operation), it is done implicitly by the SSF 17. Designated DPs in the O-BCSM instance are armed as EDP-N.
In one particular embodiment, the SSF 17 may apply the following implicit arming of DPs, as indicated in the following Table.
Some of the DPs may be armed as an EDP-R, and other as an EDP-N. The rationale why in this exemplary embodiment it is indicated that O_Answer be implicitly armed as EDP-N is that the reporting of the Answer event should not lead to suspension of the call process. If the BCSM instance in the SSF 17 would be suspended as a result of reporting the Answer event, then the speech connection between the calling party and the MSC 18 is not established. As a result, there could be (minimal) additional delay in full speech path establishment. The other events indicated relate to call establishment failure or call clearing. For those events, (minimal) additional delay in call processing is not harmful. A further rationale for arming e.g. the O_Disconnect DP as EDP-R is that, according to existing IN rules, at least one DP shall be armed as EDP-R in order for the IN service to be able to release the call.
The implicit arming rules that need to be applied depends on the IN service that is invoked. An SSF 17 may have different sets of internally defined IN service trigger data for different IN services. One such set of IN service trigger data may contain a TDP-N as the detection point and (optionally) a set of implicit arming rules.
After the SSF 17 has implicitly armed the DPs, the SSF 17 applies pre-arranged end rules, as per regular IN methodology. Applying pre-arranged end rules entails the following check:
IF any detection points are armed OR any reports are pending
THEN maintain IN relationship;
ELSE terminate IN relationship.
Implicit arming of DPs, as described relating to embodiments of the present invention, has the effect that the condition as defined after the IF statement is fulfilled; the IN relationship is therefore maintained.
From the moment that the call establishment continues, the IN service simultaneously continues in accordance with existing IN methodology. That means that when a call event occurs, such as Answer, then this event will be reported to the SCP 16, depending on the arming state of the corresponding DP at that moment.
Exemplary embodiments are illustrated in the message sequences as shown in the
In the example shown in
In the example shown in
In the example shown in
Service termination requires no additional mechanism; the SSF 17 resources will be released when the call terminates and the service is terminated as described above.
The Initial DP Result (message TC_Continue[Initial DP Result] as shown in the
Implicit disarming rules are defined for a specific IN protocol, such as CS1 or Camel Application Part v2 (CAP v2). If a different set of implicit disarming rules are applied or when implicit arming rules are applied, then the following options exist:
A different protocol (dedicated Application Context) is used. The serving SCP 16 uses the appropriate protocol stack for this service, including the implicit arming and implicit disarming rules that are defined for this protocol.
The implicit arming and implicit disarming rules are conveyed to the service logic, e.g. by means of an Extension container in the IDP operation. This method would be suitable if the implicit (dis)arming rules and pre-arranged end rules are handled by the service logic, rather than by the SCP 16.
The implicit arming and implicit disarming rules are conveyed to the SCP, e.g. by means of an information element in the TCAP dialogue portion.
In the embodiments described above, implicit arming is applied at service invocation. In a further embodiment, implicit arming is also applied at designated DPs, such as the DP O_Answer (DP7 in
In the embodiments of the present invention as described above, the BCSM in the MSC 18/SSF 17 is the Originating BCSM, and the DPs used in the examples are the DPs of the O-BCSM. As will be clear to the skilled person, the present invention is also applicable to other BCSMs, such as the T-BCSM (Terminating BCSM) in GMSC (Gateway MSC) and T-BCSM in VMSC (Visited MSC). The invention may also be applied for trunk based triggering; that is, cases whereby service triggering takes place in an arbitrary MSC 18 in the communication network, not being the serving MSC, GMSC or VMSC for the call.
In addition, the principle of the invention may also be applied to the State Models that are used for CAMEL control of SMS (Short Message Service, in MSC or SGSN (Serving GPRS Serving Node) and CAMEL control of GPRS (in SGSN and GGSN (Gateway GPRS Serving Node)).
Furthermore, it is foreseeable that embodiments of the present invention may also be applied to other network types than GSM/UMTS. When IN service triggering takes place in the wire line network (PSTN), then the implicit arming of DPs take place in e.g. a Local Exchange or Transit Exchange.
The present invention may also be described in more generalised embodiments, with reference to the
In
In
In
In
In
In
The steps taken by the various elements in the telecommunications network and the intelligent network are also visualized in the timing diagram of
In the meantime, the MSC continues the call set up process, as indicated by 1204. The SSF 17 then invokes the intelligent network service (1206) using a message to the SCP 16. The SCP 16 subsequently initiates the service (1207), aligns its internal state model (1208), and reports back to the SSF 17 (1209). The SSF 17 then arms the selected group of detection points (1210) and informs the MSC 18 (1211) accordingly.
In
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/NL2007/050004 | 1/8/2007 | WO | 00 | 2/25/2010 |