Intelligent network
Encyclopedia
The Intelligent Network (IN), is the standard network architecture
specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as mobile
telecom
networks. It allows operators to differentiate themselves by providing value-added services
in addition to the standard telecom services such as PSTN, ISDN and GSM services
on mobile phone
s.
The intelligence is provided by network nodes on the service layer
, distinct from the switching
layer of the core network
, as opposed to solutions based on intelligence in the core switches
or telephone equipments
. The IN nodes are typically owned by telecommunications operators (Telecommunications Service Provider
s).
IN is supported by the Signaling System #7 (SS7) protocol between telephone network switching centers and other network nodes owned by network operators.
which is the standardization
committee of the International Telecommunication Union
, prior to this a number of telecommunications providers had proprietary IN solutions. The primary aim of the IN was to enhance the core telephony services offered by traditional telecommunications networks, which usually amounted to making and receiving voice calls, sometimes with call divert. This core would then provide a basis upon which operators
could build services in addition to those already present on a standard telephone exchange.
A complete description of the IN emerged in a set of ITU-T
standards named Q.1210 to Q.1219, or Capability Set One (CS-1) as they became known. The standards defined a complete architecture including the architectural view, state machines, physical implementation and protocols. They were universally embraced by telecom suppliers and operators, although many variants were derived for use in different parts of the world (see Variants below).
Following the success of CS-1, further enhancements followed in the form of CS-2. Although the standards were completed, they were not as widely implemented as CS-1, partly because of the increasing power of the variants, but also partly because they addressed issues which pushed traditional telephone exchanges to their limits.
The major driver behind the development of the IN system was the need for a more flexible way of adding sophisticated services to the existing network. Before IN was developed, all new feature and/or services that were to be added had to be implemented directly in the core switch systems. This made for very long release cycles as the bug hunting and testing had to be extensive and thorough to prevent the network from failing. With the advent of IN, most of these services (such as toll free numbers and geographical number portability) were moved out of the core switch systems and into self serving nodes (IN), thus creating a modular and more secure network that allowed the services providers themselves to develop variations and value-added services to their network without submitting a request to the core switch manufacturer and wait for the long development process. The initial use of IN technology was for number translation services, e.g. when translating toll free numbers to regular PSTN numbers. But much more complex services have since been built on IN, such as Custom Local Area Signaling Services (CLASS) and prepaid telephone calls.
The interfaces between the SSP and the SCP are SS7
based and may look familiar to those familiar with TCP/IP
protocols. The SS7 protocols implement much of the OSI seven-layer model. This means that the IN standards only had to define the application layer
which was called the Intelligent Networks Application Part or INAP
. The INAP messages are encoded using ASN.1
.
The interface between the SCP and the SDP is defined in the standards to be an X.500
Directory Access Protocol or DAP. A more lightweight interface called LDAP
has emerged from the IETF
which is considerably simpler to implement, so many SCPs have implemented that instead.
and Japanese variants also exist. The main reasons for producing variants in each region was to ensure interoperability between equipment manufactured and deployed locally (for example different versions of the underlying SS7 protocols exist between the regions).
New functionality was also added which meant that variants diverged from each other and the main ITU-T standard. The biggest variant was called Customised Applications for Mobile networks Enhanced Logic
, or CAMEL for short. This allowed for extensions to be made for the mobile phone
environment, and allowed mobile phone operators to offer the same IN services to subscribers while they are roaming
as they receive in the home network.
CAMEL
has become a major standard in its own right and is currently maintained by 3GPP
. The last major release of the standard was CAMEL phase 4. It is the only IN standard currently being actively worked on.
The Advanced Intelligent Network (AIN) is the variant of Intelligent Network developed for North America by Bellcore (now Telcordia).
The standardization of the AIN was performed by Bellcore (now Telcordia Technologies
) on behalf of the major US operators.
The original goal of AIN was AIN 1.0, which was specified in the early 1990s (AIN Release 1, Bellcore SR-NWT-002247, 1993). AIN 1.0 proved technically infeasible to implement, which led to the definition of simplified AIN 0.1 and AIN 0.2 specifications. In North America, Telcordia Special Report SR-3511 (originally known as 1129+) and Telcordia Generic Requirements document GR-1129-CORE protocols are used to link switches with the IN systems such as Service Control Point
s (SCPs) or Service Nodes. Telcordia SR-3511 details a TCP/IP-based protocol which directly connects the SCP and Service Node. Telcordia GR-1129-CORE provides generic requirements for an ISDN based protocol which connects the SCP to the Service Node via the SSP.
Nevertheless, new technologies and architectures are emerging, especially in the area of VoIP and SIP
. More attention is being paid to the use of API
s in preference to protocols like INAP and new standards have emerged in the form of JAIN and Parlay
. From a technical view, the SCE is beginning to move away from its proprietary graphical origins and is moving towards a Java
application server
environment.
Network architecture
Network architecture is the design of a communications network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation.In...
specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as mobile
Global System for Mobile Communications
GSM , is a standard set developed by the European Telecommunications Standards Institute to describe technologies for second generation digital cellular networks...
telecom
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
networks. It allows operators to differentiate themselves by providing value-added services
Value-added service
A value-added service is popular as a telecommunications industry term for non-core services, or in short, all services beyond standard voice calls and fax transmissions. However, it can be used in any service industry, for services available at little or no cost, to promote their primary business...
in addition to the standard telecom services such as PSTN, ISDN and GSM services
GSM services
GSM services are a standard collection of applications and features available to mobile phone subscribers all over the world. The GSM standards are defined by the 3GPP collaboration and implemented in hardware and software by equipment manufacturers and mobile phone operators...
on mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s.
The intelligence is provided by network nodes on the service layer
Service layer
In intelligent networks and cellular networks, service layer is a conceptual layer within a network service provider architecture. It aims at providing middleware that serves third-party value-added services and applications at a higher application layer...
, distinct from the switching
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
layer of the core network
Core network
A core network, or network core, is the central part of a telecommunication network that provides various services to customers who are connected by the access network. One of the main functions is to route telephone calls across the PSTN....
, as opposed to solutions based on intelligence in the core switches
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
or telephone equipments
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
. The IN nodes are typically owned by telecommunications operators (Telecommunications Service Provider
Telecommunications Service Provider
A telecommunications service provider or TSP is a type of communications service provider that has traditionally provided telephone and similar services...
s).
IN is supported by the Signaling System #7 (SS7) protocol between telephone network switching centers and other network nodes owned by network operators.
Examples of IN services
Examples of such services are:- TelevotingTelevotingTelevoting, telephone voting or phone voting is a method of decision making and opinion polling conducted by telephone. Televoting can also extend to voting by SMS text message via a mobile cell phone.- Broadcast contest televoting :...
- Call screeningCall screeningCall screening is the process of evaluating the characteristics of a telephone call before deciding how or whether to answer it.Some methods may include:* listening to the message being recorded on an answering machine or voice mail...
- Telephone number portabilityTelephone number portabilityTelephone number portability can refer to:*Mobile number portability - telephone number portability for mobile phone users*Local number portability - telephone number portability for land-line users...
- Toll free callsToll-free telephone numberA toll-free, Freecall, Freephone, 800, 0800 or 1-800 number is a special telephone number which is free to the calling party, and instead the telephone carrier charges the called party the cost of the call...
/ Freephone - Prepaid callingPrepaid telephone callsPrepaid telephone calls are a popular way of making telephone calls which allow the caller to control spending without making a commitment with the telephone company....
- Account card calling
- Virtual private networks (e.g. : Family group calling)
- CentrexCentrexCentrex is a portmanteau of central exchange, a kind of telephone exchange.In the United Kingdom, British Telecom markets this service as FeatureLine .-Use of Centrex:...
service (Virtual PBX) - Private-number plans (with numbers remaining unpublished in directories)
- Universal Personal Telecommunication service (a universal personal telephone number)
- Mass-calling service
- Prefix free dialing from cellphones abroad
- Seamless MMSMultimedia Messaging ServiceMultimedia Messaging Service, or MMS, is a standard way to send messages that include multimedia content to and from mobile phones. It extends the core SMS capability that allowed exchange of text messages only up to 160 characters in length.The most popular use is to send photographs from...
message access from abroad. - Reverse charging
- Home Area Discount
- Premium Rate calls
- Call distribution based on various criteria associated with the call
- Location Based Routing
- Time based routing
- Proportional call distribution (e.g. between two or more call centres or offices).
- Call Queueing
- Call transfer
History and key concepts
The IN concepts, architecture and protocols were originally developed as standards by the ITU-TITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
which is the standardization
Standardization
Standardization is the process of developing and implementing technical standards.The goals of standardization can be to help with independence of single suppliers , compatibility, interoperability, safety, repeatability, or quality....
committee of the International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
, prior to this a number of telecommunications providers had proprietary IN solutions. The primary aim of the IN was to enhance the core telephony services offered by traditional telecommunications networks, which usually amounted to making and receiving voice calls, sometimes with call divert. This core would then provide a basis upon which operators
Telephone company
A telephone company is a service provider of telecommunications services such as telephony and data communications access. Many were at one time nationalized or state-regulated monopolies...
could build services in addition to those already present on a standard telephone exchange.
A complete description of the IN emerged in a set of ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
standards named Q.1210 to Q.1219, or Capability Set One (CS-1) as they became known. The standards defined a complete architecture including the architectural view, state machines, physical implementation and protocols. They were universally embraced by telecom suppliers and operators, although many variants were derived for use in different parts of the world (see Variants below).
Following the success of CS-1, further enhancements followed in the form of CS-2. Although the standards were completed, they were not as widely implemented as CS-1, partly because of the increasing power of the variants, but also partly because they addressed issues which pushed traditional telephone exchanges to their limits.
The major driver behind the development of the IN system was the need for a more flexible way of adding sophisticated services to the existing network. Before IN was developed, all new feature and/or services that were to be added had to be implemented directly in the core switch systems. This made for very long release cycles as the bug hunting and testing had to be extensive and thorough to prevent the network from failing. With the advent of IN, most of these services (such as toll free numbers and geographical number portability) were moved out of the core switch systems and into self serving nodes (IN), thus creating a modular and more secure network that allowed the services providers themselves to develop variations and value-added services to their network without submitting a request to the core switch manufacturer and wait for the long development process. The initial use of IN technology was for number translation services, e.g. when translating toll free numbers to regular PSTN numbers. But much more complex services have since been built on IN, such as Custom Local Area Signaling Services (CLASS) and prepaid telephone calls.
SS7 architecture
The main concepts (functional view) surrounding IN services or architecture are connected with SS7 architecture:- Service Switching Function (SSF) or Service Switching Point (SSP) This is co-located with the telephone exchange itself, and acts as the trigger point for further services to be invoked during a call. The SSP implements the Basic Call State Machine (BCSM) which is a Finite state machineFinite state machineA finite-state machine or finite-state automaton , or simply a state machine, is a mathematical model used to design computer programs and digital logic circuits. It is conceived as an abstract machine that can be in one of a finite number of states...
that represents an abstract view of a call from beginning to end (off hook, dialing, answer, no answer, busy, hang up, etc.). As each state is traversed, the exchange encounters Detection Points (DPs) at which the SSP may invoke a query to the SCP to wait for further instructions on how to proceed. This query is usually called a trigger. Trigger criteria are defined by the operator and might include the subscriber calling number or the dialled number. The SSF is responsible for entertaining calls requiring value added services.
- Service Control Function (SCF) or Service Control Point (SCP) This is a separate set of platforms that receive queries from the SSP. The SCP contains service logic which implements the behaviour desired by the operator, i.e., the services. During service logic processing, additional data required to process the call may be obtained from the SDF. The logic on the SCP is created using the SCE.
- Service Data Function (SDF) or Service Data Point (SDP) This is a database that contains additional subscriber data, or other data required to process a call. For example, the subscribers prepaid credit which is remaining may be an item stored in the SDF to be queried in real time during the call. The SDF may be a separate platform, or is sometimes co-located with the SCP.
- Service Management Function (SMF) or Service Management Point (SMP) This is a platform or cluster of platforms that operators use to monitor and manage the IN services. It contains the managment database which stores the services configuration, collects the statistics and alarms, and stores the Call Data Reports and Event Data Reports.
- Service Creation Environment (SCE) This is the development environment used to create the services present on the SCP. Although the standards permit any type of environment, it is fairly rare to see low level languages like CC (programming language)C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
used. Instead, proprietary graphical languages have been used to enable telecom engineers to create services directly. The languages usually belong to 4G languagesFourth-generation programming languageA fourth-generation programming language is a programming language or programming environment designed with a specific purpose in mind, such as the development of commercial business software. In the history of computer science, the 4GL followed the 3GL in an upward trend toward higher...
, the user can use Graphical Interface to manipulate between different functions to formulate a service.
- Specialized Resource Function (SRF) or Intelligent Peripheral (IP) This is a node which can connect to both the SSP and the SCP and delivers additional special resources into the call, mostly related to voice data, for example play voice announcements or collect DTMF tones from the user.
Protocols
The core elements described above use standard protocols to communicate with each other. The use of standard protocols allows different manufacturers to concentrate on different parts of the architecture and be confident that they will all work together in any combination.The interfaces between the SSP and the SCP are SS7
SS7
SS-7 can stand for:* Signaling System #7, a set of telephone signaling protocols.* The R-16 missile, with NATO reporting name SS-7 Saddler.* China Railways SS7, an electric locomotive model in China.* Super Socket 7, a chip socket introduced by AMD...
based and may look familiar to those familiar with TCP/IP
Internet protocol suite
The Internet protocol suite is the set of communications protocols used for the Internet and other similar networks. It is commonly known as TCP/IP from its most important protocols: Transmission Control Protocol and Internet Protocol , which were the first networking protocols defined in this...
protocols. The SS7 protocols implement much of the OSI seven-layer model. This means that the IN standards only had to define the application layer
Application layer
The Internet protocol suite and the Open Systems Interconnection model of computer networking each specify a group of protocols and methods identified by the name application layer....
which was called the Intelligent Networks Application Part or INAP
INAP
The Intelligent Network Application Part is a signalling protocol used in the intelligent network architecture. It is part of the SS7 protocol suite, typically layered on top of TCAP.It can also be termed as logic for controlling telecommunication services migrated from traditional switching...
. The INAP messages are encoded using ASN.1
Abstract Syntax Notation One
Data generated at various sources of observation need to be transmitted to one or more locations that process it to generate useful results. For example, voluminous signal data collected by a radio telescope from outer space. The system recording the data and the system processing it later may be...
.
The interface between the SCP and the SDP is defined in the standards to be an X.500
X.500
X.500 is a series of computer networking standards covering electronic directory services. The X.500 series was developed by ITU-T, formerly known as CCITT, and first approved in 1988. The directory services were developed in order to support the requirements of X.400 electronic mail exchange and...
Directory Access Protocol or DAP. A more lightweight interface called LDAP
Lightweight Directory Access Protocol
The Lightweight Directory Access Protocol is an application protocol for accessing and maintaining distributed directory information services over an Internet Protocol network...
has emerged from the IETF
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite...
which is considerably simpler to implement, so many SCPs have implemented that instead.
Variants
The core CS-1 specifications were adopted and extended by other standards bodies. European flavours were developed by ETSI, American flavours were developed by ANSIAmerican National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
and Japanese variants also exist. The main reasons for producing variants in each region was to ensure interoperability between equipment manufactured and deployed locally (for example different versions of the underlying SS7 protocols exist between the regions).
New functionality was also added which meant that variants diverged from each other and the main ITU-T standard. The biggest variant was called Customised Applications for Mobile networks Enhanced Logic
Customised Applications for Mobile networks Enhanced Logic
Customised Applications for Mobile networks Enhanced Logic, or CAMEL for short, is a set of standards designed to work on either a GSM core network or UMTS network. They allow an operator to define services over and above standard GSM services/UMTS services...
, or CAMEL for short. This allowed for extensions to be made for the mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
environment, and allowed mobile phone operators to offer the same IN services to subscribers while they are roaming
Roaming
In wireless telecommunications, roaming is a general term referring to the extension of connectivity service in a location that is different from the home location where the service was registered. Roaming ensures that the wireless device is kept connected to the network, without losing the...
as they receive in the home network.
CAMEL
Customised Applications for Mobile networks Enhanced Logic
Customised Applications for Mobile networks Enhanced Logic, or CAMEL for short, is a set of standards designed to work on either a GSM core network or UMTS network. They allow an operator to define services over and above standard GSM services/UMTS services...
has become a major standard in its own right and is currently maintained by 3GPP
3GPP
The 3rd Generation Partnership Project is a collaboration between groups of telecommunications associations, known as the Organizational Partners...
. The last major release of the standard was CAMEL phase 4. It is the only IN standard currently being actively worked on.
The Advanced Intelligent Network (AIN) is the variant of Intelligent Network developed for North America by Bellcore (now Telcordia).
The standardization of the AIN was performed by Bellcore (now Telcordia Technologies
Telcordia Technologies
Telcordia Technologies, formerly Bell Communications Research, Inc. or Bellcore, is a telecommunications research and development company based in the United States created as part of the 1982 Modification of Final Judgment that broke up American Telephone & Telegraph...
) on behalf of the major US operators.
The original goal of AIN was AIN 1.0, which was specified in the early 1990s (AIN Release 1, Bellcore SR-NWT-002247, 1993). AIN 1.0 proved technically infeasible to implement, which led to the definition of simplified AIN 0.1 and AIN 0.2 specifications. In North America, Telcordia Special Report SR-3511 (originally known as 1129+) and Telcordia Generic Requirements document GR-1129-CORE protocols are used to link switches with the IN systems such as Service Control Point
Service Control Point
A service control point is a standard component of the Intelligent Network telephone system which is used to control the service. Standard SCPs in the telecom industry today are deployed using SS7, Sigtran or SIP technologies. The SCP queries the service data point which holds the actual...
s (SCPs) or Service Nodes. Telcordia SR-3511 details a TCP/IP-based protocol which directly connects the SCP and Service Node. Telcordia GR-1129-CORE provides generic requirements for an ISDN based protocol which connects the SCP to the Service Node via the SSP.
Future
While activity in development of IN standards has declined in recent years, there are many systems deployed across the world which use this technology. The architecture has proved to be not only stable, but also a continuing source of revenue with new services added all the time. Manufacturers continue to support the equipment and obsolescence is not an issue.Nevertheless, new technologies and architectures are emerging, especially in the area of VoIP and SIP
Session Initiation Protocol
The Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...
. More attention is being paid to the use of API
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
s in preference to protocols like INAP and new standards have emerged in the form of JAIN and Parlay
Parlay
'Parlay/OSA' was an open API for the telephone network. It was developed by The Parlay Group, which worked closely with ETSI and 3GPP, which all co-publish it. Within 3GPP, Parlay is part of Open Services Architecture.- Overview :...
. From a technical view, the SCE is beginning to move away from its proprietary graphical origins and is moving towards a Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
application server
Application server
An application server is a software framework that provides an environment in which applications can run, no matter what the applications are or what they do...
environment.
See also
- Intelligent computer networkIntelligent computer networkAn intelligent computer network is a computer network in which the network is in control of application creation and operation. Relatively dumb terminal and devices on the network periphery access centralized network services on behalf of their users...
- IP Multimedia SubsystemIP Multimedia SubsystemThe IP Multimedia Subsystem or IP Multimedia Core Network Subsystem is an architectural framework for delivering Internet Protocol multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project , as a part of the vision for evolving mobile...
- NGIN
- Service layerService layerIn intelligent networks and cellular networks, service layer is a conceptual layer within a network service provider architecture. It aims at providing middleware that serves third-party value-added services and applications at a higher application layer...
- Value-added serviceValue-added serviceA value-added service is popular as a telecommunications industry term for non-core services, or in short, all services beyond standard voice calls and fax transmissions. However, it can be used in any service industry, for services available at little or no cost, to promote their primary business...