31-12-2009, 07:54 PM
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ABSTRACT
The seminar gives an in depth ideas of how the network has evolved from one in which switch based service logic provided services to one in which service-independent advanced intelligent network (AIN) capabilities allow for service creation and deployment.
While IN provides a network capability to meet the ever-changing needs of customers, network intelligence is becoming increasingly distributed and complicated. The introduction of the IN/1 marked the first time that service logic was external to switching systems and located in databases called service control Points (SCPs).
Also discussed are the various aspects of service creation- the tool that builds the representation of the call flow for each individual customer.
We describe the services that companies have developed using AIN/IN technology. Some services are tariffed , deployed in the network, and generate revenues. Others are in the market or technical trials, getting ready for deployment .There are other services that are either planned for deployment or were developed for demonstration purposes.
Definition
An intelligent network (IN) is a service-independent telecommunications network. That is, intelligence is taken out of the switch and placed in computer nodes that are distributed throughout the network. This provides the network operator with more means to develop and control services. Once introduced, services are easily customized to meet individual customer's needs.
1. NETWORK EVOLUTION
1.1 Plain Old Telephone Service (POTS)
Prior to the mid-1960s, the service logic, as shown in Figure 1, was hardwired in switching systems. Typically, network operators met with switch vendors, discussed the types of services customers required, negotiated the switching features that provided the services, and finally agreed upon a generic release date for feature availability.
This process was compounded for the network operator with switching systems from multiple vendors. As a result, services were not offered ubiquitously across an operator's serving area. So a customer in one end of a city, county, or state may not have the same service offerings as a person in another part of the area.
Also, once services were implemented, they were not easily modified to meet individual customer's requirements. Often, the network operator negotiated the change with the switch vendor. As a result of this process, it took years to plan and implement services.
This approach to new service deployment required detailed management of calling patterns, providing new trunk groups to handle calling patterns. As customer calling habits changed (longer call lengths, larger calling areas, and multiple lines in businesses and residences) the demand on network operators increased.
1.2 Stored Program Control (SPC)
In the mid-1960s, stored program control (SPC) switching systems were introduced. SPC was a major step forward because now service logic was programmable where, in the past, service logic was hardwired. As a result, it was now easier to introduce new services. Nevertheless, this service logic concept was not modular. It became increasingly more complicated to add new services because of the dependency between the service and the service-specific logic.
1.3 Common Channel Signaling Network (CCSN)
Another aspect of the traditional services offerings was the call setup information-that is, the signaling and call supervision that takes place between switching systems and the actual call. When a call was set up, a signal and talk path used the same common trunk from the originating switching system to the terminating switching system. Often there were multiple offices involved in the routing of a call. This process seized the trunks in all of the switching systems involved. Hence, if the terminating end as busy, all of the trunks were set up unnecessarily.
The network took a major leap forward in the mid- 1970s with the introduction of the common channel signaling network (CCSN), or SS7 network for short. Signaling system number 7 (SS7) is the protocol that runs over the CCSN. The SS7 network consists of packet data links and packet data switching systems called signaling transfer points (STPs).
The SS7 network (see Figure 2) separates the call setup information and talk path from the common trunk that runs between switching systems. The call setup information travels outside the common trunk path over the SS7 network. The type of information transferred included permission for the call setup whether or not the called party was busy.
1.4 Common Channel Signaling
SS7 technology frees up trunk circuits between switching systems for the actual calls. The SS7 network enabled the introduction of new services, such as caller ID.
Caller ID provides the calling party's telephone number, which is transmitted over the SS7 network.
The SS7 network was designed before the IN concept was introduced. However, telephone operators realized that there were many advantages to implementing and using SS7 network capabilities.
2. THE INTRODUCTION OF IN
During the mid-1980s, regional Bell operating companies (RBOCs) began requesting features that met the following objectives:
rapid deployment of services in the network
vendor independence and standard interfaces
opportunities for non- RBOCs to offer services for increased network usage
Telcordia Technologies responded to this request and developed the concept of Intelligent Network 1 (IN/1), shown in Figure 3
The introduction of the IN/1 marked the first time that service logic was external to switching systems and located in databases called service control Points (SCPs). Two services evolved that required IN/1 service logic- 800 ( or Freephone) service and the calling-card verification....... Because of the service specific nature of the technology, these services required two separate SCPs. To communicate with the associated service logic, software was deployed in switching systems. This switching system software enabled the switching system to recognize when it was necessary to communicate with an SCP via the SS7 network.
With introduction of the SCP concept, new operations and management systems became necessary to support service creation, testing, and provisioning. In the above figure, note the term " service- specific management systems" under the box labeled " service management systems". This means that the software- defined hooks or triggers are specific to the associated service. For example, an 800 service has an 800-type trigger at the switching system, an 800-service database at the SCP, and an 800-service management system to support the 800 SCP. In this service- specific environment, the 800- service set of capabilities cannot be used for other services( e.g., 900 service). Although the service logic is external to the switching system, it is still service specific.
At first glance, Figure 4 looks similar to Figure 3. However, there is one fundamental difference. Notice the wording " service- independent management systems" under the box labeled " service management system". Now, following the IN/800 service specific example, the AIN service- independent software has a three- digit trigger capability that can be used to provide a range of three-digit services (800,900,XXX,etc) as opposed to 800 service specific logic. Likewise, the SCP service logic and the service management system are service- independent, not service specific. AIN is a service- independent network capability!
3. BENEFITS OF INTELLIGENT NETWORKS
The main benefit of intelligent networks is the ability to accomplish the following:
Introduce new services rapidly- IN provides the capability to provision new services or modify existing services throughout the network with physical intervention.
Provide service customization- Service providers require the ability to change the service logic rapidly and efficiently. Customers are also demanding control of their own services to meet their individual needs.
Establish vendor independence-A major criterion for service providers is that the software must be developed quickly and inexpensively. To accomplish this, suppliers must integrate commercially available software to create the applications required by service providers.
Create pen interfaces-Open interfaces allow service providers to introduce network elements quickly for individualized customer services. The software must interface with other vendors' products while still maintaining stringent network operations standards. Service providers are no longer relying on one or two vendors to provide equipment and software to meet customer requirements.
AIN technology uses the embedded base of stored program-controlled switching systems and the SS7 network. The AIN technology also allows for the separation of service-specific functions and data from other network resources. This feature reduces the dependency on switching system vendors for software development and delivery schedules. Service providers have more freedom to create and customize services.
The SCP contains programmable service- independent capabilities( or service logic) that are under the control of service providers. The SCP also contains service-specific data that allows service providers and their customers to customize services. With the IN, there is no such thing as one size fits all- services are customized to meet individual needs.
Because service logic is under the service provider's control, it is easier to create services in a cost- effective manner. Network providers can offer market- focused service trials by loading service logic in an SCP and triggering capabilities in one or more switching systems.
Accepted standards and open, well-documented interfaces provide a standard way of communicating between switching systems and SCPs, especially in a multi vendor environment.
4. AIN RELEASE 1 ARCHITECTURE
Figure 5 shows the target AIN Release 1 architecture.
The service switching point(SSP) in this diagram is an AIN-capable switching system. In addition to providing end users with access to the network and performing any necessary switching functionality, the SSP allows access to the set of AIN capabilities .The SSP has the ability to detect requests for AIN- based services and establish communications with the AIN service logic located at the SCPs. The SSP is able to communicate with other network systems(e.g., intelligent peripherals) as defined by the individual services.
The service control point (SCP) provides the service control. There are two basic parts to an SCP. One part is the application functionality in which the service logic is installed after the services have been created. This application functionality sits on top of the second basic SCP part- a set of generic platform functionalities that are developed by SCP vendors. This platform functionality is shared among the service logic application functionality. The platform functionality also provides the SS& interface to switching systems. As shown in the figure above, the SCP is connected to SSPs by the SS7 network.
The intelligent peripheral (IP) provides resources such as customized and concatenated voice announcements, voice recognition, and dual-tone multi-frequencies (DTMF) digit collection. The IP contains a switching matrix to connect users to these resources. In addition, the IP supports flexible information interactions between an end user and the network. It has the resource management capabilities to search for idle resources, initiate those resources, and then return them to their idle state.
The interface between the SSP and the IP is an integrated services digital network (ISDN), primary rate interface (PRI), and/or basic rate interface (BRI). The IP has the switching functionality that provides the ISDN interface to the switching system.
The adjunct shown in the diagram above is functionally equivalent to an SCP, but it is connected directly to an SSP. A high speed interface supports the communications between an adjunct and an SSP. The application-layer messages are identical in content to those carried by the SS7 network between the SSP and SCP.
5. THE CALL MODEL
The call model is a generic representation of SSP call-processing activities required to establish, maintain, and clear a basic call. The call model consists of point in calls (PICs), detection points (DPs), and triggers. These are depicted in Figure 6-
PICs represent the normal switching system activities or states that a call goes through from origination termination. For example, the null state or the idle state is when the SSP is actually monitoring the customer's line. Other examples of states, or PICs, are off- hook( or originating attempt), collecting information, analyzing information, routing, alerting, etc.
Switching systems went through several changes before AIN was developed. However, the advent of AIN introduced a formal call model to which all switching systems must adhere. In this new call-model, trigger detection points (TDPs) were added between the PICs. SSPs check TDPs to see if there are any active triggers.
There are three types of triggers: subscribed or line-based triggers, group-based triggers, and office-based triggers. Subscribed triggers are provisioned to the customer's line so that any calls originating from or terminating to that line would encounter the trigger. Group- based triggers are assigned to groups of subscribers- e.g., business groups. Any member of a software-defined group will encounter the trigger. Office- based triggers are available to everyone who is connected to the telephone switching office or has access to the North American numbering plan. Office based triggers are not assigned to individuals or groups.
If an active trigger is detected, normal switching system call processing is suspended until the SSP and SCP complete communications. For example, in the diagram above, suppose an AIN call has progressed through the null state or the off-hook PIC and is currently at the collecting- information PIC. Normal call processing is suspended and the information-collected TDP because of an active off-hook delayed trigger. Before progressing to the next (analyze information) PIC, the SSP assembles an information-collected message and sends it to the SCP over the SS7 network. After SCP service logic acts on the message, the SCP sends an analyze-route message that tells the SSP how to handle the call before going to the next PIC (analyze information).
Essentially, when the SSP recognizes that a call has an associated AIN trigger, the SSP suspends the call processing while querying the SCP for call routing instructions. Once the SCP provides the instruction, The SSP continues the call model flow until completion of the call. This is basically how call model works, and it is an important part of AIN. This concept differs from the pre-AIN switching concept in which calls were processed from origination state to the call- termination state without call suspension.
6. AIN RELEASE 0
The AIN Release 0 call model has three trigger check points (TCPs). At each TCP there one or more triggers. For example, the off-hook TCP includes the off-hook immediate trigger. If a subscriber's line is equipped with this trigger, communications with the SCP will occur if the switching system detects an off-hook condition. For an off-hook delayed trigger, one or more digits are dialed before triggering the SCP. AT the digit-collection and analysis TCP, collected digits are analyzed before triggering. Triggering may also occur at the routing stage of a call. This call model is shown in Figure 7.
When a switching system recognizes that a call requires AIN involvement, it checks for overloaded conditions before communicating with the SCP. This process is called code gapping. Code gapping allows the SCP to notify the switching system to throttle back messages for certain NPAs. When code gapping is in effect, some calls may receive final treatment. For others, a provide instruction message is sent to the SCP. Depending on the SCP service logic, it will respond to the switching system with any of the call-processing instructions shown in the Figure 8.
AIN Release 0 provided 75 announcements at the switching system. Release 0 was based on American National Standards Industry (ANSI) Transaction Capability Application Part (TCAP) issue 1. TCAP is at layer 7 of the SS7 protocol stack. This means that there is only one message sent from the SSP to the SCP, no matter what the trigger is hit at any of the three TCPs.
6.1 AIN RELEASE 0.1
AIN 0.1 is the first subset of AIN Release 1. There are two fundamental differences between AIN Release 0 and AIN 0.1 The first in a formal call model and the second is the messaging sets between the switching system and the SCP. The formal call model is separated into the originating call model (originating half call) and the terminating call model (terminating half call). The AIN Release 0 call model did not distinguish between originating and terminating. A standard or formal call model is necessary as we evolve to the target AIN Release 1 capability, because the capabilities will have more PICs and TDPs. Also, there will be multiple switch types and network elements involved. Therefore, the service logic will need to interact with every element that will be required in the network.
The AIN 0.1 originating call model includes four originating trigger detection points- originating attempt, information collected, information analyzed, and network busy.
The AIN 0.1 terminating call model includes one TDP - termination attempt.
AIN 0.1 : SSP-SCP Interface
The AIN 0.1, as shown in Figure 9, is based on ANSI TCAP issue 2, which means that the message set is different than the message set in ANSI TCAP issue 1. For example, in AIN Release 0, there is only one message sent from the SSP to the SCP no matter what trigger is hit at any of the three TCPs. In AIN 0.1, separate messages are sent for the four originating and one terminating TDP.
6.2 AIN RELEASE 0.2
AIN 0.2 builds on AIN 0.1 with additional capabilities to support two service drivers- phase 2 personal communication service (PCS) and voice- activated dialing (VAD). While AIN 0.2 is focused on capabilities to supports PCS and VAD, all requirements for these capabilities are defined in a service-independent manner. AIN 0.2 capabilities will include the following:
ISDN-based SSP- IP interface
busy and no-answer triggers
next event lists processing
default routing
additional functions in all operations areas( e.g., network testing)
The two primary AIN 0.2 capabilities are the ISDN interface between a switching system and an ISDN-capable device (such as an IP) and the addition of busy and no-answer triggers.
Next event list processing is another capability. In addition to TDPs, AIN 0.2 includes event detection points (EDPs). With EDPs, the SCP will have the ability to send a next-event list to the SSP. This next-event list is used by the SSP to notify the SCP of events included in the next-event list. These events may include busy, no answer, terminating resource available, etc.
AIN 0.2, also includes default routing capabilities. This means that when calls encounter error conditions, they can be sent to a directory number, an announcement, etc., as opposed to sending it to final treatment, as is the case in AIN 0.1.
AIN 0.2 SSP-IP Interface
AIN Release 0 and AIN 0.1 assumed that the announcements were switch-based. With the introduction of 0.2 announcements can reside in an external database, such as an IP.
If the SCP sends a send-to-resource message to the switching system to have the IP play an announcement or collect digits, the switching system connects the customer to the IP via the SSP-IP ISDN interface. The end user exchanges information with the IP. The IP collects the information and sends it tot the switching system, which in turn forwards the information to the SCP. One of the fundamental switching system capabilities is the internetworking of SS7 (SCP) messages with the ISDN messages (SSP-IP).
In addition the SSP may control IP resources without SCP involvement. VAD is an example. A VAD subscriber could be connected tot he IP voice-recognition capabilities. The VAD subscriber says " call mom" and the IP returns mom's telephone number to the switching system. The switching system recognizes mom's number as if the subscriber had actually dialed the number.
7. AIN SERVICE CREATION EXAMPLES
The previous modules addressed the architecture and theory of the AIN. This section will discuss various aspects of service creation- the tool that builds the representation of the call flow for each individual customer. Many AIN software vendors have paired service to eliminate the need for traditional programming methods. Through the use if menu-driven software, services are created by inputting various service parameters.
7.1 Building-Block Approach
Play announcement, collect digits, call routing, and number translation building blocks are shown here. The SSP has the ability to play announcement and collect digits, as does the IP. Routing the call is an SSP function, and number translation is an SCP capability. By arranging these four capabilities or building blocks in various combinations.
7.2 Service Creation Template
Figure represents what a service creation template might look like. For an outgoing call screening service, the service begins with the customer's telephone number. This example allows the customer to screen 900 numbers, while still having the ability to override 900 screening by entering a PIN. Except for 703-974-1234, all non-900 calls are processed without screening.
7.3 Extension Dialing Service
A four-digit extension dialing service is displayed in Figure . It allows for abbreviated dialing beyond central-office(CO) boundaries. If an employee at location 1 wants to call an employee at location 2 by dialing the extension number 111, 2111 would be dialed. Although 2111 is not a number that a switching system can use to route the call, a customized dialing plan trigger is encountered after 2111 is dialed and a query is sent to the SCP. Service logic at the SCP uses the 2111 number to determine the real telephone number of the called party.
7.4 Disaster Recovery Service
Figure illustrates a disaster recovery service. This service allows business to have calls routed to one or more alternate locations based on customer service logic at the SCP. Calls come into the switching system by the normal location. After triggering, communication with the SCP occurs. Based on the service logic, the call could be either routed to the normal business location or to one or more alternate business locations.
7.5 Area Number Calling Service
An area number calling (ANC) service is shown in Figure . This service is useful for companies or businesses that want to advertise one telephone number but want their customer's calls routed to the nearest or most convenient business location. The SCP service logic and data (e.g., zip codes) are used to make a match between the calling party's telephone number and geographic location. The call is hen routed to the company or business location that is closest to or most convenient for the calling party.
7.6 Do-Not-Disturb Service
Figure displays a do-not-disturb service. This is a service in which the Smith family has terminating screening service logic at the SCP. Whenever someone calls them, the service logic determines whether the call should be routed to the Smith's telephone or an announcement should be played. In this particular case, a telemarketer calls the Smith family. The SCP tells the switching system to route the telemarketer to an announcement.
The customers' SCP service logic may also contain a list of numbers that they want to get through while do not disturb is active. In that case, if the SCP finds a match between the calling party number and a number on the list, the call is routed to the Smith family.
8. OTHER AIN SERVICES
The following list describes the services that companies have developed using AIN/IN technology. Some services are tariffed, deployed in the network, and generate revenues. Others are in the market or technical trials, getting ready for deployment .There are other services that are either planned for deployment or were developed for demonstration purposes.
N11 access service- With this service, a unique code is used to access a service gateway to information service providers (ISPs), such as newspapers or libraries. The subscriber may either preselect an ISP for automatic routing or request block calls to ISPs.
Basic routing- Basic routing function allows the subscriber to route calls to a single destination as defined in the system.
Single number service- Routing by single number service allows calls to have different call treatments based on the originating geographic area and the calling party identification.
Routing by day of week- The routing by day-of-week function allows the service subscriber to apply variable call routings based on the day of the week that the call is placed.
Routing by time of day- The routing by time of day function allows service subscribers to apply variable call routings based on time of the day that the call is made.
Selective routing- This service is tied to the call- forwarding feature generally offered as a switch- based feature. With the AIN, when a call to a selective routing customer is forwarded, the SCP determines where to route the forwarded call based on the caller's number.
Call allocator - The call allocator service feature allows the service subscriber to specify the percentage of calls to be distributed randomly up to five alternate call handling treatments.
Alternate destination on busy (ADOB)- The ADOB service feature allows the service subscriber to specify a sequence of destinations to which calls will be routed if the first destination is busy.
Command routing- A service subscriber predefines a set of alternate call treatments to handle traffic in cases of emergency, unanticipated or anticipated demand peaks, or for any other reason that warrants an alternate call treatment.
Automatic route selection/least cost routing- With this service subscribers design a priority route for every telephone number dialed. The system either directs calls or block calls to restricted privilege users.
Work-at-home- This service allows an individual to be reached at home by dialing an office number, as well as allowing the employee to dial an access code from home, make long- distance calls, and have them billed and tracked to a business telephone number.
Holding room- Transportation companies' passengers use this service to inform families or business associates of transportation delays or cancellations.
Call counter- The call counter service feature increases a counter in the tele-voting (TV) counting application when a call is made to a TV number. The counts are managed in the SCP, which can accumulate and send the results during a specific time period.
Advertising effectiveness service- This service collects information on incoming calls. This information is useful to advertisers to determine the demographics of their customers.
Virtual foreign exchange service- uses the public switched network to provide the same service as wired foreign exchange service.
Automated customer name and address( ACNA)- ACNA enables customers to block their lines from being accessed by the service.
AIN for the case teams (ACT)- ACT allows technicians to dial from a customer premise location anywhere in the service region and connect to a service representative supported by an ACD. Through voice prompts, the technician is guided to the specific representative within a case team pool within seconds, with no toll charges tot he customer.
Regional intercept- Regional intercept instructs callers of new telephone numbers and locations of regional customers. This service also forwards calls to the new telephone number of the subscriber. Various levels of the service can be offered, based upon the customer's selection.
Work at home billing- A person who is working at home dials a 4- digit feature access code, which prompts the system to track and record the billing information for the calls. Calls tracked in this manner are billed directly to the company rather than to the individual.
Inbound call restriction- This service allows a customer to restrict certain calls from coming into the subscribers location. This service is flexible enough to restrict calls either by area code, NNX, or particular telephone numbers. Restrictions may even be specified by day of week or time of day.
Flexible hot line- This service allows a customer to pick up a telephone handset and automatically connect to a merchant without dialing any digits. An example of this is a rent-a-car phone in an airport, which allows a customer to notify the rent -a-car company to pick them up at the terminal.
CONCLUSION
The main benefit of intelligent networks is the ability to accomplish the following:
Introduce new services rapidly- IN provides the capability to provision new services or modify existing services throughout the network with physical intervention.
Provide service customization- Service providers require the ability to change the service logic rapidly and efficiently. Customers are also demanding control of their own services to meet their individual needs.
Establish vendor independence-A major criterion for service providers is that the software must be developed quickly and inexpensively. To accomplish this, suppliers must integrate commercially available software to create the applications required by service providers.
Create pen interfaces-Open interfaces allow service providers to introduce network elements quickly for individualized customer services. The software must interface with other vendors' products while still maintaining stringent network operations standards. Service providers are no longer relying on one or two vendors to provide equipment and software to meet customer requirements.
REFERENCES
¢ ieee.com
¢ MITlabs.com
¢ iec.com
¢ itpaper.com
¢ detnews.com
¢ technologyreview.com
¢ mobileinfo.com
¢ zdnet.com
CONTENTS
1. NETWORK EVOLUTION
1.1 Plain Old Telephone Service (POTS)
1.2 Stored Program Control (SPC)
1.3 Common Channel Signaling Network (CCSN)
1.4 Common Channel Signaling
2. THE INTRODUCTION OF IN
3. BENEFITS OF IN
4. AIN RELEASE 1 ARCHITECTURE
5. THE CALL MODEL
6. AIN RELEASE 0
6.1 AIN RELEASE 0.1
6.2 AIN RELEASE 0.2
7. AIN SERVICE CREATION EXAMPLES
7.1 Building-Block Approach
7.2 Service Creation Template
7.3 Extension Dialing Service
7.4 Disaster Recovery Service
7.5 Area Number Calling Service
7.6 Do-Not-Disturb Service
8. OTHER AIN SERVICES
9. REFERENCE
ACKNOWLEDGEMENT
I express my sincere gratitude to Dr. Agnisarman Namboodiri, Head of Department of Information Technology and Computer Science , for his guidance and support to shape this paper in a systematic way.
I am also greatly indebted to Mr. Saheer H. and
Ms. S.S. Deepa, Department of IT for their valuable suggestions in the preparation of the paper.
In addition I would like to thank all staff members of IT department and all my friends of S7 IT for their suggestions and constrictive criticism.
