1 .WIN Principle
- Master the structure of WIN
- Master the function of each unit in WIN
- Understand the concepts in BCSM
- Understand the typical flow in WIN
Ok, let’s take a look course arrangement. Firstly, an introduction to the motivation of intelligent network, in the following three sections, the architecture of intelligent network will be explained, Including the function and components of TELLIN system. And TELLIN is trade mark of Huwei IN products. After that, a brief introduction to the IN concepts model in the fifth section and WIN Application Protocol in the sixth section. Then the BCSM, including the important concepts in IN. at last, the WIN typical flow is explained in detail.
With the development of society, economy, and technology, we need more and more new services.
There are two traditional methods to provide the new telecom services:
We can update the software and hardware of the switching system for the new service, and we can also design a totally new and relatively independent system for it.
Let’s take a look of the first method, updating the software and hardware of the switching system. There are several disadvantages:
- In the whole network, there are many equipment providers, each provider should update their software or hardware for one new service, and all equipment in the network should update their version. Obviously, it would take a long time.
- Different provider maybe has different understanding for the same specifications, so when their equipment interconnects, there will bring new potential security trouble to switching.
- And more unfortunately, using this method, unable to provide many complicated services, which needs a central database.
Then the second method, To design a totally new and relatively independent system.
Also, it would take a long period to design a new system, and it should be very expensive only for one service, it is too wasteful to utilize the network resource fully and efficiently. So generally, this method is hardly adopted by the operators and provides.
IN Recommendations are motivated by the interests of telecommunication services providers too rapidly, cost effectively and differentially satisfy their existing and potential market needs for services. Also, these service providers seek to improve the quality and reduce the cost of network service operations and management.
To provide telecom services rapidly, economically, flexibly and efficiently, there should be a totally new means. That is the appearance of Intelligent Network.
All telecom services, simple or complex, aim to connect the two parties (calling and called) and provide them with a channel to communicate. Since the traditional switching and transmission network can perform this perfectly. The Intelligent Network leaves the user access and circuit switch of an IN service call to the traditional switching and transmission network, while the control of the service flow is assigned to the IN Layer. This is soul of the Intelligent Network: Service is separated from switching.
The traditional switching and transmission layer fulfill the task of user access, circuit switching and connecting, etc. While the Intelligent Network Layer decides how the switching and transmission layer should do. That means the service flow is controlled by the Intelligent Network Layer. To realize this design, the two layers should communicate with each other. Since their communication decides the call processing
directly, real-time and high reliability are the most important. CCS#7 signaling system seems to be the optimal communication means. Then there comes the CCS#7 signaling Layer.
Because the intelligent layer provides the control function, we can also say, the main idea of the intelligent network is that control function is separated from the switching function.
1.2 Architecture of Intelligent Network
So, what is the intelligent network? In the second section, the architecture of the intelligent network is introduced.
In the transmission and switching layer, there are two kinds of equipment, SSP and IP.
The intelligent layer consists of SCP, SDP, SMS and SCE. The connection between the two layers is via the STP.
The meaning of each abbreviation is shown in this slide:
- SCE --- Service Creation Environment
- SMS --- Service Management System
- SCP --- Service Control Point
- STP --- Signaling Transfer Point
- SSP --- Service Switching Point
- IP --- IN Peripherals
1.3 Components of TELLIN System
After the brief introduction to the architecture of IN, TELLIN system will be talked about, including the components of TELLIN system in the third section and functions of each unit in TELLIN system in the fourth section.
In this section, the components of TELLIN system.
TELLIN System is a common intelligent network platform product come from Huawei. TELLIN System supports Telecom service operation and management for both PSTN and Mobile network. TELLIN system provides lots of services, such as Account Card Call, Prepaid Service , Advertisement, Telephone Votes, Virtual Private Network, etc. Up to April, 2000, TELLIN system has provided services for more than 100 million subscribers and more than 20 sorts of intelligent services. TELLIN system has vastly installed in national trunk network, province network, local network in china. The China National Mobile Intelligent Network is the first commercial system which adopts CAMEL PHASE II. Up to now, the number of mobile subscribers are more than 2 million. The TELLIN system is also installed in oversea market, including Kenya national intelligent network, Thailand national Mobile intelligent network, Uzbekistan Mobile intelligent network, Algeria Mobile intelligent network, Peru intelligent network, and Zimbabwe international intelligent network.
What is the function of the TELLIN system? Simply speaking, the function of TELLIN system is to provide integrated service solution for PSTN, Mobile network, IP network. Including Service Operation, management and new services design , creation and testing. TELLIN system is service independent and supports multiple service execution simultaneously. The service provider can run multiple services on one TELLIN platform. The service provider can also manage all services in online mode. So the service provider can very easily add new service, change service status, modify service features, add new subscriber, modify subscriber, allocate and maintain network resource. Finally, the most important thing is that the service provider can very easily design, create and test new service by using TELLIN-SCE, a component of TELLIN system.
1.4 Function of each unit in TELLIN System
Ok, in the fourth section, let’s talk more detail about functions of each unit in TELLIN system.
At first, SSP. This is typically an upgraded digital telephone exchange.
As the exchange, It has the functions, such as, calling control function, service switching function, and calling control access function.
As to a IN call, SSP has nothing to do with how to handle it. Usually when SSP encounter a IN call, it will suspend the local call processing and send the message to SCP, and then handle the call according to the instruction from SCP. So another function of SSP is that it can pass information about the call to SCP and allow the SCP to control how it (the SSP) handles the call.
So, generally, if you want to take one MSC/VLR as one SSP, you should update it.
Another equipment in transmission and switching layer is IP.
This is a system which provides extra features such as playing announcements, collecting user information.
Playing announcement and collecting user information are important resource to IN.
Besides, IP can provide the basic call connection function.
IP can be in one physical entity with SSP, and also can be separated.
Then the intelligent layer. The intelligent layer contains 3 components: Service Management System (SMS), Service Control Point (SCP) and Service Creation Environment (SCE).
SCP is very important in this layer. The switching layer should connect to the intelligent layer, and send IN call information to it, actually, it is SCP. The other equipment in the intelligent layer doesn’t connect with switching layer.
TELLIN SCP is the device used to store Service Logic Programs (SLP), service data, subscriber data, charge data, network resource data. SLP is the program executed to control IN calls .SCP is the device used to execute SLP to control IN call process. SCP cooperates with SSP/IP to control IN call, including receives and analyzes IN call events reported from SSP, executes SLPs and sends instructions to request SSP/IP to control the call process and control SSP/IP to play prompt and collect user's input.
SCP is managed by the SMS . The operator can use SMS to load and active new service on the SCP or modify the features of old service. The operator can also use SMS to perform tasks such as subscriber management, charging management , network management and modify the correspond data on SCP.
SCP is service independent and supports multiple service simultaneously.
So, What is the function of TELLIN SCP. Generally speaking, function of TELLIN SCP includes the following:
- To invoke different SLPs (Service Logical Procedure)
- To send calling control instruction to SSP
- Database function
The first two functions belong to Service Control Function. It is the function used to manage the features of IN service and control IN call process and charging.
The Database Function is the function used to manage a database upon which all service data, subscriber data, charging data, network resource data were stored. SDF function includes also service data access authentication function. Only authorized user can access to the service database.
Ok, lets continue to discuss service management system of TELLIN system. It is system used by the service provider to manage the Service Logic Programs, service data, subscriber data, charge data, network resource data etc. And the SMS is service independent. The service provider can manage many services by using SMS.
The SMS consists of SMP and SMAP. The SMP is a group of server program used to perform service management function. The SMAP is a client program. It provides friendly graphic user interface and the operator needs just to click some menu on it to finish all service management jobs. Usually, we need only several SMP installed in center device room and many SMAP distributed over all business hall.
The function of SMS includes the follow:
- Service management function
- Subscriber management function
- Network management function
- System Management function
- Statistic Reports form function
The Service management function is used to register a new service and load it to SCP, then activate it and open to the public. After the service is out of time, the service provider can deactivate it and delete it finally.
The Subscriber management function is used to create new subscriber and load it to SCP, then activate it and allow the people to access it. The service provider can modify or deactivate, even delete it finally.
The Network management function is used to set up network configuration of components in the TELLIN system, including network configuration of SCP, SAU and SSP.
The Charging management function is used to maintain a group of charge table. Charge table contains charge control information used by SCP to charge a call.
The System Management function is used to define SMAP nodes configuration and operator and make sure that only authorized SMAP and operator can connect to SMP.
The Statistic Reports form function is used to generate useful information such as call events statistic and subscriber information statistic.
SCE, Service Creation Environment. This is the computer system which contains applications for a service logic programmer to define a new service and its service logic.
Ok, now, let’s take a look of the implementation procedure for a new service and a subscriber service in intelligent network, and so that you could have a good understanding to the structure and function of IN.
First, for a new service, the service designer would generate the new service logic in SCE, and simulate, test, after that, the new logic will be sent to SMP, SMP will then load it to the SCP and activate it. Now, the new service logic is valid in SCP.
If one subscriber applies the new service, for the operator, the business staff will add the new subscriber data in SMAP to SMP, the SMP stores it and then adds it to the SCP. And then the subscriber can use the new service.
Ok, this procedure is helpful to understand the architecture of intelligent network.
1.5 INCM(IN Concepts Model)
Ok, let’s begin a new section, IN Concepts Model. This section is an overview of Intelligent Network Concepts Model. It introduces the four-lay structure of INCM.
This section is very abstract, you are only required to understand the basic concepts and structure of this model.
A Key objective of the IN is to provide service-independent functions that can be used as building blocks to construct a variety of services. This allows easy specification and design of new services.
A second key objective is network-implementation-independent provision of services. This objective aims to isolate the services from the service-independent functions which are actually implemented in various physical networks, thus providing services are independent of underlying physical network infrastructures.
The IN Concept Model should not be only considered as an architecture. It is a framework for the design and description of the IN architecture.
Various models and concepts will be used in the standardization of IN. The INCM is intended to represent an integrated, formal framework within which these concepts are identified, characterized and related. To achieve this, the INCM consists of four planes where each plane represents a different abstract view of the capabilities provided by an IN-structured network. They are service plane, global functional plane, distributed functional plane and physical plane.
Let’s take a look of them one by one.
First, service plane, It reflects the service IN provides for users. Each service is made up of service features (SF). A service can have one single service feature, or it can have several features. Like Free phone service, it needs two features: one number and reverse charging, where the call is charged to the called party, not the calling party. So, services are composed of one or more Service Features (SFs), which are the lowest level of services.
Secondly, the Global Functional Plane, The Global Functional Plane (GFP) represents all the functions of the IN, including the BCP (Basic Call Processing), SIB (Service Independent Building Block), POI (Point of Initiation) between the BCP and SIB and POR (Point of Return). As can be seen from the slide, a service feature in a service plane is realized through several SIBs in the general functional plane. In ITU-T
specifications, there are 14 standard SIBs, the service designer works out different service using these standard SIBs. The SIBs are very like the toy bricks, different combination can shape different things. SIBs, including the BCP SIB, are service independent. The relationship among the SIBs for one service feature is called Global Service Logic.
This plane is oriented to the service designer, for a service feature, in GFP, it consists of the necessary SIBs, the GSL, and input/output parameters for each SIB. BCP is a very special SIB, it is included in any service.
Then, DFP. The Distributed Functional Plane (DFP) models a distributed view of an IN-structured network. Each Functional Entity (FE) may perform a variety of Functional Entity Actions (FEAs). Any given FEA may be performed within different functional entities. However, a given FEA may not be distributed across functional entities.
Within each functional entity, various FEAs may be performed by one or more elementary functions.
Service-independent building blocks (SIBs) are realized in the distributed functional plane (DFP) by a sequence of particular FEAs performed in the functional entities. Some of these FEAs result in information flows between functional entities.
The Physical Plane (PP) models the physical aspects of IN-structured networks. The Model identifies the different physical entities and protocols that may exist in real IN-structured networks. It also indicates which functional entities are implemented in which physical entities.
Ok, let’s make a sum up the four planes.
Service Plane: reflects the service IN provides for users. And it is oriented to the subscriber.
Global Functional Plane: represents all the functions of the IN and it is oriented to the service designer.
Distributed Functional Plane: models a distributed view of an IN-structured network. It is oriented to the network designer.
Physical Plane: models the physical aspects of IN-structured networks. It is oriented to the network operator.
This slide shows the meaning of the abbreviations in the previous slides.
Then we focus on the Distributed Functional Plane and Physical Plane.
Let’s see the definition of Functional Entities.
The Call Control Access Function (CCAF):
- The CCAF is the Call Control Agent (CCA) Function that provides access for users. It is the interface between user and network call control functions.
The Call Control Function (CCF):
- The CCF is the Call Control (CC) Function in the network that provides call/connection processing and control.
The Service Switching Function (SSF):
- The SSF is the service switching (SS) function, which, associated with the CCF, provides the set of functions required for interaction between the CCF and a service control function (SCF). It
- extends the logic of the CCF to include recognition of service control triggers and to interact with the SCF;
- manages signaling between the CCF and the SCF;
- modifies call/connection processing functions (in the CCF) as required to process requests for IN provided service usage under the control of the SCF;
The Service Control function (SCF):
- The SCF is a function that commands call control functions in the processing of IN provided and/or custom service requests. The SCF may interact with other functional entities to access additional logic or to obtain information (service or user data) which are required to process a call/service logic instance. It
- provides interface for interacts with service switching function/call control function, specialized resource function (SRF) and service data function (SDF) functional entities;
- contains the logic and processing capability required to handle IN provided service attempts;
- provides interface for and interacts with other SCFs, if necessary;
- is managed, updated and/or otherwise administered by an SMF.
The Service Data function (SDF):
- The SDF contains customer and network data for real time access by the SCF in the execution of an IN provided service. It
- provides interface for interacts with SCFs as required;
- provides interface for interacts with other SDFs, if necessary;
- is managed, updated and/or otherwise administered by an SMF.
The Specialized Resource Function (SRF):
- The SRF provides the specialized resources required for the execution of IN provided services (e.g. digit receivers, announcements, conference bridges, etc.). It provides interface for and interacts with SCF and SSF (and with the CCF).
Service Creation Environment Function (SCEF):
- This function allows services provided in an intelligent network to be defined, developed, tested and input to SMF. Output of this function would include service logic, service management logic, service data template and service trigger information.
Service Management Access Function (SMAF):
- This function provides an interface between service managers and the SMF. It allows service managers to manage their services (through access to the SMF).
Service Management Function (SMF):
- This function allows deployment and provision of IN provided services and allows the support of ongoing operation.
- Particularly, for a given service, it allows coordination of different SCF and SDF instances, eg. billing and statistic information are received from the SCFs, and made available to authorized service managers through the SMAF; modifications in service data are distributed in SDFs, and it keeps track of the reference service data values.
- The SMF manages, updates and/or administers service related information in SRF, SSF and CCF.
Ok, let’s take a look of the relationship between DSP and physical plane.
One or more functional entities can be located in the same physical entity. Different functional entities contain different functions, and may also contain one or more of the same functions. In addition, one functional entity cannot be split between two physical entities; the functional entity is mapped entirely within a single physical entity. Finally, duplicate instances of a functional entity can be mapped to different physical entities, though not the same physical entity.
This table shows the relationship between the main functional entities and physical entities.
For the SSP, SSF and CCF are necessary, the SCF, SDF, SRF can be optional. If IP is integrated in SSP, then SRF should be selected.
For the SCP, SCF is mandatory, SDF can be optional.
For the SDP, it only needs the SDF.
For the IP, SRF is only mandatory Functional entity.
Ok, in this section, the keystone is the DFP and PP, also the relationship between them.
1.6 WIN Application Protocol
Ok, next section, WIN Application Protocol.
In order to introduce the intelligent network in the wireless communication system, ETSI defined CAMEL（Customized Applications for Mobile network Enhanced Logic) on GSM Phase 2+ in 1997. The CAMEL is characterized by providing the service consistency irrelevant to the service network, which is a network characteristic but not a supplementary service. Even when a subscriber is not in the HPLMN （Home Public Land Mobile Network), the CAMEL can help the network operator to provide particular services.
Actually, there are two kinds of parallel standard for WIN, one is used in North American; another is in Europe, based on GSM network. CAMEL is an European standard.
In this course, we devote to the CAMEL defined by ETSI.
Huawei TELLIN system is based on CAMEL specifications.
The CAMEL standards are divided into Phase1（V1）, Phase2（V2） and Phase3（V3）. In March, 1998, the Phase2 standardization was completed.
CAMEL adds several function entities, such as gsmSSF, gsmSRF and gsmSCF, to the GSM network structure. This slide shows the CAMEL Phase 2 network structure.
There are two CAP interfaces, gsmSSF－gsmSCF interface and gsmSCF－SRF interface. There are two new MAP interface, gsmSCF－HLR interface and MSC－gsmSCF interface.
gsmSSF－gsmSCF interface: The interface is used in the gsmSCF to control a certain gsmSSF and request the gsmSSF to set up the connection with the SRF. As an open interface, it is mainly used by the gsmSSF to send request to the gsmSCF and get its instructions.
gsmSCF－SRF interface: This interface is used by the gsmSCF to order the SRF to broadcast the recorded notice to subscribers. In the associated connection mode, the gsmSCF can send the relevant ID.
gsmSCF－HLR interface: The interface is used by the gsmSCF to request information from the HLR.
As an option for network operators, the HLR can reject the provision of information. The SCF can query the state and location information of a mobile subscriber.
MSC－gsmSCF interface: Through this interface, the MSC sends the supplementary service use notice to the gsmSCF.
Now let’s make an overview to the CAP and MAP in No.7 signaling system.
CAP（CAMEL Application Part）is based on the INAP protocol of the intelligent network. In Phase1, CAP stipulates the information flow between gsmSSF and gsmSCF. In Phase2, CAP specifies not only the interface between gsmSSF and gsmSCF, but also the interface between gsmSRF and gsmSCF.
MAP（Mobile Application Part) of the GSM system provides the necessary signaling functions for the GSM system, which are required by the No.7 signaling system to provide the necessary services (e.g. Voice and non-voice applications in the PLMN). In GSM Phase 2+, a group of MAP operations is added to meet the requirements of the CAMEL network and some modifications are done to several MAP operations.
CAP and MAP are all the application layer protocols, they belong to TCAP users, and their positions in the No.7 signaling system are shown in this figure.
As the application layer protocol based on OSI layer 7 model, CAP is used to support the interaction between the SSF, SCF, SDF and SRF -- four AEs (Application Entities ) -- of CAMEL Phase 1 and CAMEL Phase 2.
CAP operations have four types:
Type 1 Report both success and failure
Type 2 Report the failure only
Type 3 Report the success only
Type 4 Report neither success nor failure
Actually, the four types of operation are provided by TCAP. And CAP uses them.
In the CAP, 22 operations are available for your choice according to the service opening needs. The corresponding relations between the operations and the information flows are shown in this table.
Several operations in the WIN typical flow will be introduced. Here, they are not explained.
1.7 BCSM
Now, let’s begin a new section, BCSM, Basic Call State Model.
1.7.1 Components of BCSM
In this section, first, the introduction to the general handling , components of BCSM, then explanation the O_BCSM and T_BCSM, at last Important Concepts will be explained.
The BCSM provides a high-level model of GMSC- or MSC/VLR-activities required to establish and maintain communication paths for users. As such, it identifies a set of basic call activities in a GMSC or MSC/VLR and shows how these activities are joined together to process a basic call.
The BCSM is used to describe the actions in an MSC/GMSC during originating, forwarded or terminating calls.
The BCSM identifies the points in basic call processing.
This figure shows the components that have been identified to describe a BCSM.
One BCSM consists of four components, PIC (Point In Call), DP (Detection Point), Transition and events.
PICs identify MSC/VLR (GMSC) activities associated with one or more basic call/connection states of interest to IN service.
The points in processing at which notifications (to the service logic) can occur and transfer of control (to the gsmSCF) is possible are called Detection Points (DPs).
Transition describes the flow from one PIC to another PIC in basic connection handling.
Event brings the transition.
1.7.2 O_BCSM
In the ITU-T specifications, one IN call is divided into the originating and terminating parts, correspondingly, the BCSM is divided into the two parts, O_BCSM and T_BCSM.
First, let’s see the O_BCSM.
The O-BCSM is used to describe the actions in a MSC during originating (MSC) or forwarded (MSC or GMSC) calls.
When encountering a DP the O-BCSM processing is suspended at the DP and the MSC/GMSC indicates this to the gsmSSF which determines what action, if any, shall be taken in case the DP is armed.
This table shows the definition of O_BCSM DPs.
1.7.3 T_BCSM
Then, the T_BCSM.
The T-BCSM is used to describe the actions in a GMSC during terminating calls.
When encountering a DP the T-BCSM processing is suspended at the DP and the GMSC indicates this to the gsmSSF which determines what action, if any, shall be taken in case the DP is armed.
In the table the different DPs in the T-BCSM are described.
1.7.4 Important Concepts
After the overview to the BCSM, let’s study the several concepts appeared in the description of BCSM.
In this part, there are three concepts: DP, Service Key and CSI.
The detection points (DP) are the points in call at which these events are detected. The DPs for Mobile Originated Calls and Mobile Terminated Calls are described in the previous slides.
A DP can be armed in order to notify the gsmSCF that the DP was encountered, and potentially to allow the gsmSCF to influence subsequent handling of the call. If the DP is not armed, the processing entity continues the processing without gsmSCF involvement.
Three different types of DPs are identified:
Trigger Detection Point - Request (TDP-R)
- This detection point is statically armed and initiates a CAMEL control relationship when encountered. Processing is suspended when the DP is encountered.
Event Detection Point - Request (EDP-R)
- This detection point is dynamically armed within the context of a CAMEL control relationship. Processing is suspended when encountering the DP and the gsmSSF waits for instructions from the gsmSCF.
Event Detection Point - Notification (EDP-N)
- This detection point is dynamically armed within the context of a CAMEL control relationship. Processing is not suspended when encountering the DP.
The Service Key can identify to the gsmSCF the service logic that it should apply. The Service Key is a part of the O/T-CSI.
The service key identifies for the gsmSCF the requested set of one or more CAMEL services. It is used to address the correct application/SLP within the gsmSCF.
CAMEL subscriber data has several types of CSI (CAMEL Subscription Information):
They are O/T_CSI, SS_CSI, TIF_CSI and USSD_CSI.
O/T_CSI includes the SCP Address, service key, default call handling and TDP list.
SCP Address is to be used to access the gsmSCF for a particular subscriber. The address shall be an E.164 number to be used for routing.
The Default Call Handling indicates whether the call shall be released or continued as requested in case of error in the gsmSSF to gsmSCF dialogue.
The TDP List indicates on which detection point triggering shall take place. For O-CSI only DP2 is used. For T-CSI only DP12 is used.
For the other CSI, I don’t talk about it because they are not widely used.
Ok, so much for this section.
After this section, you should master the concepts of DP, CSI, and you can understand the idea of BCSM.
1.8 WIN Typical Flow
Ok, in the last section, the several typical flows in WIN will be introduced.
1.8.1 PPS Call Flow
In this section, PPS call flow and recharging flow will be introduced.
In the PPS call flow, there are three sequences in different conditions.
Number Segment Trigger, charging for calling and called Party
O/T_CSI Trigger, charging for calling and called Party
Number Segment Trigger, charging only for calling Party
First, the PPS to PPS call sequence using number segment trigger, charging for calling and called party.
In this case, the MAP version of MSC/VLR and HLR is phase 2, it doesn’t support the CSI, so the number segment trigger is adopted, the MSC/VLR/SSP distinguishes the common GSM subscriber and PPS subscriber using different number segment.
When the MSC/VLR/SSP receives the message IAM from the MSC/VLR which the PPS is registered, it should analyze the number, finds this is a PPS subscriber, then suspends the call, triggers the intelligent service to the SCP using message IDP (Initial DP). For the PPS, the real-time billing is very important, SCP should deduct the money with the conversation of PPS. In the message IDP, SSP should report the information related with billing.
Generally, for the calling party, the long-distance fee is from the actual position of calling party to the home location of called party, for the called party, it is from the actual position of called party to the home location of called party.
When SSP identifies the calling party is PPS subscriber, it sends the IDP message to the SCP, this is DP2. In this IDP message, the location number and service key are included. Service key is used to invoke the service logic for SCP. The location number is the parameter which indicates the location of calling party. From the called number, SCP knows the home location of called party. They are information related with billing. From them SCP can know the billing rate for the calling party.
When the SCP receives the IDP, it then sends the EDPs to the SSP using message RRBE (Request Report BCSM Event). The EDPs include DP 4,5,6,9,10, related with calling party. We know there are three types of DP, TDP_R, EDP_R, and EDP_N, TDP_R is configured in SSP, and EDP is stored in SCP, when SSP sends IDP to the SCP, SCP will then transmit the EDP to the SSP. When SSP detects the event, then sends report to the SCP.
After RRBE, the SCP sends AC (Apply Charging) to the SSP. In this message, the MAX call period duration is included, generally, it is 15 Minutes, every 15 Minutes, SCP sends one AC message. Of course, when the MAX call period is less then 15 Minutes, this value is not 15 Minutes.
Then SCP sends the message Continue indicating the SSP continue the call.
SSP then continues this call, then analyzes the called number, finds it is a PPS subscriber, before send IDP (DP12) to the SCP, SSP should know the called party ‘s position, so send SRI to the HLRb, the HLR gives response SRI_ACK which the MSRN is included. This sub-flow belongs to MAP sequence, I don’t talk more,
SSP sends the IDP to SCP triggering the called intelligent service. The location information is included, it indicates the actual position of called party.
SCP will then send RRBE, AC and Continue to SSP in turn. DP 13,14,17,18 is included in RRBE.
SSP will then send IAM message to the MSC/VLR which the called PPS is registered when it receives the Continue from SCP. If the called PPS is idle, the MSC/VLR sends ACM to SSP, the called subscriber rings. The SSP then sends ACM to the MSC/VLR which the calling PPS is located in. When the called subscriber answers the call, MSC/VLRb will then send ANM the SSP, in turn SSP sends it to the office which the caller is located in.
Then, the conversation between the subscribers.
When the caller releases the call at first, SSP receives the REL message. This is DP9, the calling party disconnects the call, SSP should send ERB (Event Report BCSM)to the SCPa, in which event type of BCSM (DP9) is included. This DP is a type of request, the call is suspended, SSP should wait for the instruction from SCPa.
Then ACR (Apply Charging Report) is sent to the SCP, in which the time information is included.
SCP then sends command RC (Release Call) to the SSP.
For the called party, SSP sends ERB (DP17) and ACR to the SCPb, SCPb gives instruction RC to the SSP.
Then SSP sends the REL the MSC/VLRb, MSC/VLRb gives response using message RLC. And in turn SSP sends RLC to the originating office.
Then let’s take a look of the sequence using CSI trigger.
In this case, the MAP version of MSC/VLR and HLR is phase 2 +.
For the calling party, the SSP analyzes the O_CSI, not the calling number segment, then sends the IDP (DP2) to the SCPa.
For the called party, there is no T_CSI in MSC/VLR/SSP, T_CSI is stored in HLR and MSC/VLRb. MSC/VLR/SSP send message SRI to the HLR, the HLR returns SRI_ACK, including the T_CSI, not MSRN. MSC/VLR/SSP analyzes the T_CSI, then sends IDP (DP12) to the SCPb.
After the SCP sends command “Continue” to the SSP, SSP sends another SRI to the HLR, in which “suppress T_CSI flag” is set to YES. This time the HLR returns MSRN to SSP. Then SSP sends IAM message to the MSC/VLRb, establishing the conversation between the subscribers.
When the calling PPS subscriber releases the call at first, the sequence is same with the previous one.
Ok, let’s see another call sequence from PPS to PPS.
In this sequence, No charging for called party, Charging only for calling party, charge of long distance is from the actual position of calling party to the actual position of called party, using number segment trigger.
Because charge of long distance is from the actual position of calling party to the actual position of called party, the MSC/VLR/SSP knows the location information of called subscriber before sends IDP to the SCP. So the SRI is before IDP.
After get the MSRN, SSP sends IDP to the SCPa, SCPa sends RRBE, AC, and continue.
Then trigger the called intelligent service to SCPb using message IDP.
Because no charging for the called party, so no AC message to the SSP from SCPb.
Correspondingly, when the call is released, the SSP only sends ERB to the SCPb, no ACR message.
In this sequence, I mainly devote to the difference from the previous example.
The sequence for the calling and called PPS is independent relatively. If only one party is PPS subscriber, the SSP only triggers intelligent service to SCPa(The calling party is PPS subscriber) or SCPb(The called party is PPS subscriber). The sequence will be simplified.
1.8.2 Recharging Flow
Ok, at last, let’s study the PPS recharging flow.
Generally, the PPS recharges the money using a special number, which is called access code.
When the PPS dials this number, the SSP/IP analyzes the called number, then triggers intelligent service to the SCP, using message IDP, this belongs to the access code trigger.
After receives IDP, SCP sends EDP (DP10) to the SSP, using RRBE. Then sends CTR (Connect To Resource).
If the PPS subscriber dials this number for the first time, the SCP sends PA message to the SSP/IP, indicating IP to play announcement of greeting, “welcome use Prepaid service”.
When the IP finishes the announcement, it will then send SRR (Specialized Resource Report) to the SCP. SCP then sends P&C (Prompt And CollectUserInfo), indicating play the announcement “Please select the language”.
When subscriber presses “1” for English, SSP/IP send it through the message “P&C result” to the SCP.
SCP will then sends “P&C” to the SSP/IP, indicating play announcement “press 1 for recharging, press 2 for query……”, the subscriber selects recharging, also, SSP/IP send it to the SCP via “P&C result”.
SCP will then send “P&C” to the SSP/IP indicating “please input the voucher card No. and password”. After subscriber inputs them, SSP/IP sends them to the SCP.
The SCP sends PA to the SSP/IP, telling the subscriber “Please wait a minute”. The SCP will check the voucher card No. and password; if they are legal, then Infuse money for the subscriber; and Change card state and subscriber state. Then SCP sends “PA” to SSP/IP, the SSP/IP plays announcement “you have recharged you money successfully”.
After the announcement, SSP/IP sends SRR to the SCP.
SCP will then send “P&C” to SSP/IP, SSP/IP play announcement “Press 1 for recharging, press 2 for query……”.
The subscriber then releases the call, the SSP/IP releases the resource occupied, and sends message “ERB” to the SCP. The event is DP10, the calling party abandons the call. this is a type of notice. The call is not suspended, only notice the SCP.
Ok, that’s the sequence of recharging.
Ok, we have just finished the course of the WIN principle.
In this course, we have also discussed more detail about components and functions of intelligent network, IN call handling, typical PPS signal flow. After this course, hope you already know:
- The structure of WIN
- The functions of each unit in WIN
- The concepts in BCSM
- The typical flow in WIN
If you still have questions about these topics, please refer to relative manuals.
