What is Intelligent Network?
Overview of Intelligent Network Architecture
Over the last thirty years, one of the major changes in the implementation of Public Switched Telephone Networks (PSTNs) 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 (Intelligent Network) 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 standardised. 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.
1 Objectives of the Intelligent Network
The main objectives of the IN (Intelligent Network) 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 (Intelligent Network) 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 business 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 (Intelligent Network), 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 (Intelligent Network) services are 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.
Prior to IN, due to complexity of switch based feature handling software, the considerable time frame required for service development prevented the provider from easily going back to redefine 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 (Intelligent Network) 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.
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 service 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 form 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 (SCP0.
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 (Intelligent Network) service call handling. It connects the requested resource towards a SSP upon the advice of the SCP.
Service Management Point (SMP0 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.
3 Physical Plane
Service Switching Point (SSP)
The SSP serves as an access point for IN (Intelligent Network) services. All IN services calls must first be routed through the PSTN to the “nearest” SSP. The SSP identifies the incoming call as an IN service call by analysing the initial digits (comprising the “Service Key”) dialled by the calling subscriber and launches a Transaction Capabilities Application Part (TCAP) query to the SCP after suspending further call processing. When a TCAP response is obtained from the SCP containing advice for further call processing, SSP resumes call processing.