In Arch& Services

OVERVIEW OF INTELLIGENT NETWORK ARCHITECTURE Over the last thirty years one of the major changes in the implementation of Public Switched Telephone Networks (PSTN) has been the migration from analogue to digital switches. Coupled with this change has been the growth of intelligence in the switching nodes. From a customer’s and network provider’s point of view this has meant that new features could be offered and used. Since the feature handling functionality was resident in the switches, the way in which new features were introduced into the network was by introducing changes in all the switches. This was time consuming and fraught with risk of malfunction because of proprietary feature handling in the individual switches. To overcome these constraints the Intelligent Network architecture was evolved both as a network and service architecture. In the IN architecture, the service logic and service control functions are taken out of the individual switches and centralized in a special purpose computer. The interface between the switches and the central computer is standardized. The switches utilize the services of the specialized computer whenever a call involving a service feature is to be handled. The call is switched according to the advice received by the requesting switch from the computer. For normal call handling, the switches do not have to communicate with the central computer. Objectives of the Intelligent Network The main objectives of the IN are the introduction and modification of new services in a manner which leads to substantial reduction in lead times and hence development costs, and to introduce more complex network functions. An objective of IN is also to allow the inclusion of the additional capabilities and flexibility to facilitate the provisioning of services independent of the underlying network's details. Service independence allows the service providers to define their own services independent of the basic call handling implementation of the network owner. The key needs that are driving the implementation of IN are: Rapid Service Deployment Most businesses today require faster response from their suppliers, including telecommunication operators. By separating the service logic from the underlying switch call processing software, IN enables operator to provide new services much more rapidly. Reduced Deployment Risk Prior to IN, the risk associated with the deployment of new services was substantial. Major investments had to be made in developing the software for the services and then deploying them in all of the switches. With the service creation environment available, the IN services can be prototyped, tested and accessed by multiple switches simultaneously. The validated services can then be rolled out to other networks as well. Cost Reduction Because the IN services were designed from the beginning to be reusable, many new services can be implemented by building on or modifying an existing service. Reusability reduces the overall cost of developing services. Also, IN is an architecture independent concept, i.e. it allows a network operator to choose suitable development hardware without having to redevelop a service in the event that the network configuration changes. Customization Prior to IN, due to complexity of switch based feature handling software, the considerable time frame required for service development prevented the

2 provider from easily going back to refine the service after the customer started to use it. With IN, the process of modifying the service or customization of service for a specific customer is much less expensive and time consuming. The customization of services is further facilitated by the integration of advanced peripherals in the IN through standard interfaces. Facilities such as voice response system, customized announcements and text to speech converters lead to better call completion rate and user friendliness of the services. IN Architecture Building upon the discussion in the previous section, one can envisage that an IN would consist of the following nodes: • • •

Specialized computer system for - holding services logic, feature control, service creation, customer data, and service management. Switching nodes for basic call handling Specialized resources node

The physical realization of the various nodes and the functions inherent in them is flexible. This accrues from the "open" nature of IN interfaces. Let us now look at the nodes that are actually to be found in an IN implementation. • The service logic is concentrated in a central node called the Service Control Point (SCP). • The switch with basic call handling capability and modified call processing model for querying the SCP is referred to as the Service Switching Point (SSP). • Intelligent Peripheral (IP) is also a central node and contains specialized resources required for IN service call handling. It connects the requested resource towards a SSP upon the advice of the SCP. • Service Management Point (SMP) is the management node which manages services logic, customers data and traffic and billing data. The concept of SMP was introduced in order to prevent possible SCP malfunction due to on the-fly service logic or customer data modification. These are first validated at the SMP and then updated at the SCP during lean traffic hours. The user interface to the SCP is thus via the SMP. All the nodes communicate via standard interfaces at which protocols have been defined by international standardization bodies. The distributed functional architecture, which is evident from the above discussion, and the underlying physical entities are best described in terms of layers or planes. The following sections are dedicated to the discussion of the physical and functional planes. Physical Plane Service Switching Point (SSP) The SSP serves as an access point for IN services. All IN service calls must first be routed through the PSTN to the "nearest" SSP. The SSP identifies the incoming call as an IN service call by analyzing the initial digits (comprising the "Service Key") dialed by the calling subscriber and launches a Transaction Capabilities Application Part (TCAP) query to the SCP after suspending

3 further call processing. When a TCAP response is obtained from SCP containing advice for further call processing, SSP resumes call processing. The interface between the SCP and the SSP is G.703 digital trunk. The MTP, SCCP, TCAP and INAP protocols of the CCS7 protocol stack are defined at this interface Service Control Point (SCP) The SCP is a fault-tolerant online computer system. It communicates with SSP's and the IP for providing guidelines on handling IN service calls. The physical interface to the SSP's is G.703 digital trunk. It communicates with the IP via the requesting SSP for connecting specialized resources. SCP stores large amounts of data concerning the network, service logic, and the IN customers. For this, secondary storage and I/O devices are supported. For more details refer to the chapter on the "SCP Architecture". As has been commented before, the service programs and the data at the SCP are updated from the SMP. Service Management Point (SMP) The SMP, which is a computer system, is the front-end to the SCP and provides the user interface. It is sometimes referred to as the Service Management System (SMS). It updates the SCP with new data and programs (service logic) and collects statistics from it. The SMP also enables the service subscriber to control his own service parameters via a remote terminal connected through dial-up connection or X.25 PSPDN. This modification is filtered or validated by the network operator before replicating it on the SCP. The SMP may contain the service creation environment as well. In that case the new services are created and validated first on the SMP before downloading to the SCP. One SMP may be used to manage more than one SCP's. Intelligent Peripheral (IP) The IP provides enhanced services to all the SSP's in an IN under the control of the SCP. It is centralized since it is more economical for several users to share the specialized resources available in the IP which may be too expensive to replicate in all the SSPs. The following are examples of resources that may be provided by an IP: • Voice response system • Announcements • Voice mail boxes • Speech recognition system • Text-to-speech converters The IP is switch based or is a specialized computer. It interfaces to the SSP's via ISDN Primary Rate Interface or G.703 interface at which ISUP, INAP, TCAP, SCCP and MTP protocols of the CCS7 protocol stack are defined.

The IN architecture is depicted in Fig.1

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Fig1 IN Architecture .

5 Distributed Functional Plane Functional model of IN contains nine functional entities (FE's) which are distributed over various physical entities (PE's) described in the previous section. A functional entity is a set of unique functions. Brief description of the FE's is given below. CCAF Call Control Agent Function, gives users access to the network. CCF Call Control Function provides the basic facility for connecting the transport (e.g. speech). It involves the basic switching function and trigger function for handling the criteria relating to the use of IN. SSF Service Switching Function is used to switch calls based on the advice of SCF at the SCP. This function provides a service independent interface. SCF It contains the service logic components and advises the SSF at SSP on further call handling. SDF Service Data Function contains the user related data and data internal to the network. SRF Specialized Resources Function covers all types of specialized resources other than the connection resources that are in the exchange. (e.g. recorded announcements, tones, conference bridges, etc.). SCEF Service Creation Environment Function specifies, develops, tests and deploys the services on the network. SMAF Service Management Access Function provides an interface between service management function and the service manager who may be an operator.

6 SMF Service Management Function enables a service to be deployed and used on IN. Figure 1.2 depicts the distribution and interconnection of the various function entities.

The distribution of functional entities over the physical entities and their interconnection is summarized in Tables 1–1 and 1–2 below. It may be noted that all the physical entities may not be present in all IN's as the choice of functional entities to be provisioned is entirely up to the service provider.

7

IN call setup • • • • • • • • • • • • • •

User makes an IN call by a special access code(For e.g 1600/1800) The call is routed to SSP like normal speech call The SSP identifies the IN call A query (CCS7 message) is triggered (sent) to SCP SCP searches its database and replies SSP with information asked for SSP switches the call to the subscriber based on the information from SCP Subscriber disconnects (either party release) Release detected by SSP SSP prepares the AMA for sending to billing centre SSP sends call related data to SCP SCP transfers this information at periodic intervals to SMP over X.25 links SMP does post processing of call statistics In case the call could not be completed by SSP because the subscriber is busy or No reply, SSP asks SCP for alternate number SCP may either provide alternate number or ask SSP to connect tones or annc.

8 IN implementation : Architectural alternatives Full IN •All IN components are available •As per International standards •Large number of services possible •Possible to connect multi-vendor components Cost effective IN •SCP, SMP and IP integrated in SSP •Minimal functions are provided •Low cost •Quick to implement •Proprietary BSNL Opted for Full IN. In Full IN There are two alternatives: •Integrated in PSTN •Overlay network Overlay network: •New SSPs to be installed •New network connectivity is to be made •Additional call routing •Network congestion •When IN traffic increase, SSP may be a bottleneck •Easy to implement Integrated in PSTN: •Existing exchange upgraded to SSPs •Existing network connectivity used •Optimum call routing •Multi-vendor environment •Inter working problems •Takes time to implement •Services like Televoting, VPN and Number portability are elegantly provided. New IN implementation is integrated in PSTN Based on Alcatel Platform. BSNL IN Implementation 5 IN Platforms, 9 IN Services, 12 IP/SRP’s, 4 types of SSP’s and 340 ROI’s (85 X 4). •IN Platforms 4 General Purpose IN Platforms (GPIN) at Kolkata, Lucknow, Ahmedabad, Bangalore, 1 Mass Calling IN Platform (MCIN) at Hyderabad. •

SCPs Code ƒKolkata ƒHyderabad ƒBangalore

345 424 425

9 ƒAhmedabad ƒLucknow

233 180

IP/SRP – 12 No’s of 480 ports each 3 IP/SRP’s in Kolkata, 2 IP/SRP’s at Trivandrum, One each at Lucknow, Bangalore, Ahmedabad, Hyderabad, Chennai, Ambala and Nasik Charging of IN calls To charge a call using an IN service, there are two types of charging • Network charging • Service charging Network Charging Network charging is charging for transportation of the telephone call. It only covers the usage of the telephone network by the call. Service Charging Service Charging is used to manage one or more specific services. For a service provider, it is determined by the SCF of the SCP. It is independent of the route the call takes to reach the SCP. Intelligent Network Services : Total nine services are planned in BSNL network: • Free Phone Service (FPH) • Virtual Private Network (VPN) • Virtual Card Calling Service (VCC) • Account Card Calling service (ACC) • Premium Rate Service (PRM) • Universal Access Number service (UAN) • Tele Voting • Universal Personal Number (UPN)• Number PortabilityIN Service Access Codes ƒ

FPH Service:

1600 XXX

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VCC Service:

1602 XXX

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ACC Service:

1604 XXX

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PRM Service:

0900 XXX

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VPN Service:

1601 XXX

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Tele-voting(one unit):

1902 424

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Tele-voting(Two unit):

1904 424

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Tele-voting(Higher rate):

1903 424

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Tele-voting(No charge):

1603 424

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Universal Number Local(UNL):

1901 XXX

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Universal Number L.D (UND):

0901 XXX

10 ƒ

Universal Personnel Number

0902XXX

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UAN Management

1907XXX

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UPN Management

1908XXX

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VPN Management

1909XXX

Common Definitions applied to all IN Services Network Operator: The network operator provides the network operating elements and resources for the execution of IN services. This includes the Intelligent Network components. Service Provider: The service provider offers the service for subscription. The service provider may be a bank or Account Card Company or the network operator. Service provider commercially manages the service and also manages the billing arrangement. Service Subscriber: The subscriber is a person or legal entity having a contractual relationship with a service provider on behalf of one or more service users. The service subscriber is responsible for payment of charges to the service provider. Service User: The service user is the person or entity who can access the service. VCC (Virtual Card Calling) India Telephone Card(ITC) : This service allows the subscriber to place calls from any normal access interface to any destination number and have the cost of these calls charged to the account specified by the Virtual Card Calling (VCC) number, which does not refer either to the calling line or the called line. Virtual Card Calling service is an access code based service. All Virtual card calls are preceded by the access code 1602XXX. After dialling the access code, the subscriber is prompted to enter the Virtual Card no. User dials his account number for validation. The numbers give the unique identification of subscriber. The validation is done at the SCP. After his authentication check, he is prompted to dial the destination number. User can make call only if he has a balance in his account. Virtual Card Calling Service Access Procedure: •

Dial 1602 XXX.

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You will be prompted to dial your card number.

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You will be prompted the balance amount in the account followed by request to dial the destination number.

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A VCC Call: 1602 345<16 digit card No.>

VCC Features: Follow-on call

11 This feature allows the service user to set up a new call bypassing the card number input procedure. This feature applies in the following cases: After called number input: • Destination in provider outgoing black list, • Not enough credit to make the call, • Busy condition, • No reply condition, • Congestion condition. In this case, the service user receives the appropriate warning announcement and is invited to enter a new called number. After completion of call (depends on SSP type), When the called party hangs up if the remaining credit is greater than the minimum credit threshold to use the service, the service user is invited to enter a new called number. Language selection This feature allows the service user to receive announcements in different languages. Provider incoming black list This feature enables the service provider to bar service access to a list of calling party numbers. This black list is made of numbers and is defined for the service. A fault announcement is sent to the service subscriber when the call is restricted. This feature is used to reduce the fraudulent activity. Provider outgoing black list This feature enables the service provider to bar calls according to a list (For example: emergency numbers, services numbers, ...). This black list is made of prefixes (first digits or full numbers) and is defined in the card profile. When the call is restricted, the service user receives a warning announcement and is invited to enter a new called number. Predefined promotional number This feature enables to attach a predefined called number to a promotional card profile. In this case the call parameter input phase is by-passed and the call is routed to this pre-defined number. National/International Calls Restriction This feature enables to allow or restrict the national/international calls for a VCC card. A local VCC card can make local calls only, a national VCC card can make local as well as national calls and an international VCC card can make local, national and international calls. This feature is defined by the service provider in the card profile. Credit Limit : This feature allows to supervise the credit allowed to a service user.

12 Minimum credit to use the service: If the account balance is less than a minimum credit threshold, the call is routed to a fault announcement Minimum credit to make the call: This feature enables to check if the credit is enough to establish the desired call (according to the tariff). Then if there is not enough credit to make the call, the call is routed to a fault announcement. Real time credit supervision: During call progress, the remaining credit is checked in real time. Then if the credit limit is reached, the call is released. Warning tone: During call progress, when the credit goes to the warning threshold, the service user receives a tone. This feature is SSP dependent feature. Payphone restriction: This feature enables to bar calls from telephone box calls for a VCC card. Account Card Calling Service: General Description This service allows the subscriber to place calls from any normal access interface to any destination number and have the cost of these calls charged to the account specified Account Card Calling (ACC) number, which does not refer either to the calling line or the called line. Account Card Calling service is an access code based service Account card. Calls are preceded by the access code 1604XXX. After dialing the access code, the subscriber is prompted to enter the Account Card no followed by the Personal Identification Number (PIN). User dials his Account card number and PIN for validation. These two numbers give the unique identification of subscriber. The validation is done at the SCP. After successful authentication, the user is prompted to dial the choice, i.e. a destination number or PIN modification or balance enquiry. If the subscriber goes for PSTN call then he will he prompted for the destination number and accordingly the call is routed, else the subscriber will be prompted for new PIN or the subscriber is played the balance amount announcement. Account Card Calling Service Access Procedure: ƒ

Dial 1604 XXX from any telephone.

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You will be prompted to dial the card no. & PIN.

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Again, you will be prompted to put your choice if the card no. & PIN are found to be validated.

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Choice 1 to dial the destination number. You can dial any type of call opted during subscription.

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Choice 2 to modify PIN, you can modify PIN any number of times.

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Choice 3 for knowing balance amount.

ACC Call: 1604 345 <8 digits card No. & 4 digits PIN><1><destination> ACC Features: Language SelectionƒMultiple Simultaneous Calls ƒCall log ƒPredefined

13 ƒFollow

On Calls ƒProvider Incoming/Outgoing Black ListFree Phone, Universal Access Number, Universal personal Number, Premium Rate Number Features common to FPH, UAN, UPN, PRM • Call Forwarding Conditional-CFC (On No Answer or Busy) • Origin Dependent Routing (ODR) This service feature allows the subscriber to have calls routed according to the calling party's area of origination. Based on the area of origination the subscriber can also accept or reject the call. •

Origination Call Screening (OCS) This service feature allows the subscriber to bar the calls originating from certain areas identified by their area codes.

•

Time Dependent Routing (TDR) This service feature enables the subscriber to route calls based on time of day, day of week and day of year. The precedence when more than one type of parameters are specified for determining routing shall be 1. Day of year 2. Day of week 3. Time of day

Free Phone Services General Description Here the concept of reverse charging is applied with additional features. The service subscriber will have one logical number against more than one PSTN no. distributed all over the network. He can have his own routing plan using Time Dependent Routing, Origin Dependent Routing facilities. Free Phone Services Access procedure: • The user can make a free phone call using the following dialing procedure. •

Dialing plan: 1600 XXXYYYY

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Access code : 1600XXX

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Free phone number: YYYY (4 digits)

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SCP ID : XXX

Premium Rate Services General Description Premium Rate service enables service subscribers to provide value added information based services to the users. The service provider allocates a logical number to the service Subscriber, which is known as Premium Rate number. The calls made to the Premium Rate number are charged at a higher rate than the normal calls. The revenue generated by the Premium Rate calls

14 is shared between the Service Provider and the Service Subscriber as per the terms agreed between them. The Premium Rate service allows a call made to the Premium Rate number to be routed to different destinations depending upon the criteria defined by the subscriber (i.e., ODR, TDR, CFC, etc.). The Premium Rate user accesses the service by dialing the Premium Rate Number as advertised by the service subscriber. The Premium Rate service logic translates this number depending on the conditions stated above. Different types of information based services can be provided in the Premium Rate service. For example, Premium Rate service may provide information related to stock markets, astrology, weather, consultation services, etc. Access Procedure The user can make a Premium Rate call by dialing 0900XX YYYY; where Access code = 0900XX SCP ID = XXX Premium Rate number = YYYY (4 digits). Universal Access Number Service: General Description This service allows a subscriber to publish a national number and have the incoming calls routed to different destinations based on various criteria such as the geographical location of the caller, the time, the day or the date on which the call is made. The UAN subscriber can subscribe for local UAN or National UAN and correspondingly there are two access codes 1901XXX (for local UAN) and 0901XXX (for National UAN). A subscriber subscribed as local UAN (i.e. the default treatment is a local directory number) can be reached by using either of the access codes. However if a subscriber is a national UAN (i.e. the default treatment is a STD number), it can be reached only by 0901XXX while when dialed with 1901XXX, the call fails. Access Procedure The user can make a UAN call using the following dialing procedure. Dialing Plan: 1901XX/0901XXX - YYYY Access code: 1901XXX/0901XX SCP ID: XXX UAN number: YYYY (4 digits) Universal Personnel Number (UPN): General Description This service allows a subscriber to publish a national number and have the incoming calls routed to different destinations based on various criteria such as the geographical location of the caller, the time, the day or the date on which the call is made. The main difference between UAN and UPN is UPN subscriber can make outgoing calls and charging will be done against UPN account. It is providing Mobility in fixed Network • Dialing: 0902 XXX YYYY SCP ID XXX UPN Number YYYY

15 Tele-Voting Service: General Description This service allows the subscriber to conduct telephonic public opinion polls and surveys. Persons wishing to respond to an opinion poll can call the advertised Televoting numbers to register their votes. Using this service, the network operator can temporarily allocate a single telephone number to the Televoting subscriber with the last two (maximum) digits, called the 'Choice Digits', as variable. Most of the Televoting calls are routed to an announcement which acknowledges the call. Simultaneously, the choice counters shall be incremented. Facility shall exist to route selected calls to a public number. After voting has ceased, the service subscriber shall be supplied the results, i.e., the contents of the choice counters. Types of Televoting There are two types of televoting supporting 1. Called charged (1603XXX) 2. Calling charged (1902XXX,1904XXX,1903XXX) All other features are the same for the two services except the party which is charged. In 1603XXX, called party/televoting subscriber is charged while in 1902XXX, the calling party bears the expenses. Access Procedures The user accesses this service using the following dialling procedure. Dialing Plan: 1603XXXTTTTDD/1902XXXTTTTDD Access code: 1603XXX / 1902XXX SCP ID = XXX Televoting number: TTTT (4 digits) plus DD (2 digits), (i.e. Choice Digits) as variable. Virtual Private Network: General Description The Virtual Private Network (VPN) service enables subscribers to establish a private network using PSTN resources. The subscriber lines connected to different network switches constitutes a virtual Private Automatic Branch Exchange (PABX). A VPN subscriber can define his own dialing and routing plan between all his destination locations and configure them as if they were on a PABX, using the PSTN resources. The VPN call is charged to the service subscriber's account. VPN user can originate calls to other members of their own group and calls to external public numbers. They can also make calls into the VPN from external public numbers and also use VPN resources from any external Public number in the network to call any other external Public number. The service also allows online modification of authorization code by the user. Number Portability on Fixed Network: The Fixed Number Portability service allows PSTN user to switch network operator or geographical area without changing their existing directory

16 number. The F-NP is an operator oriented IN service. This means that the provided service has no direct relation with the end-user. Location Portability, i.e., the ability to retain an existing directory number when changing from one physical location to another, while still remaining in the same operator network Service Provider Portability, shall allow the subscribers to change service providers without changing their phone number Access Equipment portability, enabling porting of entire sequence number series and/or of non-sequential groups of individual numbers.