CHAPTER I. INTRODUCTION TO SIGNALING SYSTEM No.٧

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1 CHAPTER I INTRODUCTION TO SIGNALING SYSTEM No.٧ ١-١ INTRODUCTION Signaling may be described as interchange of information between different functional parts of a telecommunication system. The main purpose for using signaling in modern telecom networks is to transfer control information between different network nodes. Signaling System No.٧ is a protocol developed for the implementation of Communications between entities existing within a network to provide the instructors. It is a standard, universally accepted way to transfer information between compatible switching offices following packet-data switching conventions. The SS٧ network is a self healing network that maximizes its efficiency and effectiveness by using redundant nodes and links. The information transferred through the SS٧ network may be categorized as one of the following: Information concerning the set-up and tear-down of calls (call processing for cellular or wire line) Information concerning inquires to databases (data base queries such as credit card validations. ٨٠٠ translations, etc.) Information used to maintain the integrity of the SS٧ network (Network Management and maintenance) So we will speak about the procedure and component of all processing, database and network management. Then we will view the bearer network and the signaling in general, and what is the position of SS٧ signaling to all signaling.

2 - ٢ - At the end of this chapter I will describe the basic structure, concept, SS٧ link type and network element of the SS٧. During the ١٩٧٠s, Data communication was developing more and more rapidly. Different vendors of data communication systems were developing their own standards for data communication processes, leading to a number of closed islands of vendor-dependent systems. This diversity of emerging standards was not in the best interests of the users and an increasing need for international data communication standards was obvious. The increasing need for communication between different computer systems lead to the work on an international standard. This was started around ١٩٧٧/٧٨ by ISO (International Standard Organization) after an initiative by BSI (British Standard Institute). The objective was to create a standard that makes it possible to interconnect data communication systems all over the world in ١٩٨٠; ISO presented the result of this standardization work in the form of the OSI Reference Model. OSI is an abbreviation for Open Systems Interconnection. Open Systems are systems that use the standardized communication procedures developed from the reference model. Thus all such Open Systems will be able to communicate with each other. Open systems may be computers, exchanges, data networks etc. In ١٩٨٤, CCITT (Committee Consultative International Telegraph Telephone) came out with the recommendation X.٢٠٠, where the OSI reference model is described in detail. The key aspects of the OSI reference model are layering services and protocols. All previous introduction was for chapter ٢ addresses where we will list the OSI model layers and the schematic of the information which will been added in each layer. SS٧ structure will be describe and compared with OSI model to clarify the relationship between OSI and SS٧. Chapter three is list the three type of the basic message format used within the SS٧ protocol, those messages are the fill in signaling unit (FISU), link status unit (LSSU) and message signaling unit (MSU) which is the most important message in SS٧ protocol and represent more than ٩٥ % of the ISUP message. Definition of all fields is described;

3 - ٣ - All type of MTP (Message Transfer Part) is classify in three level, where function and name of the message for each level will be listed including some test procedure, alignment, initiated, detection and correction,where all kinds of policing is list in the end of this chapter. TUP or the Telephone User Part was the first SS٧ call control protocol to be designed by the ITU-T and establishes a framework protocol for the exchange of messages designed to describe call set-up and teardown. These messages are used in the correct sequence to ensure that the relevant information is sent from the originating SP to the required destination and that the destination can signal back information regarding its availability to accept the call. ISUP or ISDN User Part describes signaling functions relating to the management and setup of telephone calls that can include voice, non-voice and data transmission. The ISUP procedures and protocol are described in ITU-T documents Q٧٦١-٧. It builds on the principles of the TUP and extends its capabilities to include full integration with the ISDN access network. This means that calls that require end-to-end data transmission can be established across the network. ISUP also supports many additional services, such as those found in private networks (PBX networks). Due to the many enhancements, many countries are migrating towards an ISUP based network. TUP and ISUP message format going to be describe in details where we will know what the value of SI in SIO field is for each, and what the name of all message in each user part and what is the heading code of each. Also I have talk about the interworking with non SS٧ networks; finally a call setup processing and some traffic cases is describe by example and by capture message,using signaling protocol analyzer. The Signaling Connection Control Part (SCCP) offers enhancements to the MTP Level ٣ to provide connectionless and connection-oriented network services, as well as to address translation capabilities. Figure ٥.١ shows the SCCP enhancements to the MTP services provide a network service that is equivalent to the OSI Network Layer ٣. The Signaling Connection Control Part (SCCP) was introduced by ITU-T (former CCITT) ١٩٨٤ (Red Book). It is defined in ITU-T's recommendations Q.٧١١- Q.٧١٦. The SCCP provides additional functions to the Message Transfer Part (MTP) to cater for

4 - ٤ - connectionless as well as connection oriented network services, to transfer circuit related and non-circuit related signaling information and other types of information between exchanges and specialized centers in telecommunication networks(e.g. for management and maintenance purposes). The addressing capabilities of SCCP extend those found in MTP, which is limited to delivering a message to a specified node and using a four-bit service indicator to distribute messages within a node. SCCP supplement this capacity by providing addressing that uses Destination Points Codes (DPC) plus Subsystem Numbers (SSN). The SSN is local addressing information that identifies each of SCCP users at a node. Another addressing enhancement is the ability to address messages with global titles, such as dialed digits, that are not in a form usable by MTP for routing. SCCP provides a mapping facility for translating global title into an address of the form DPC+SSN. The SCCP is a functional entity situated above the Message Transfer Part (MTP). Together the SCCP and the MTP form the Network Service Part (NSP) which meets the requirements for the network layer (layer ٣) of the OSI model. The overall capabilities of the SCCP are to provide the means for: Logical signaling connections within the SS٧ network. A transfer capability for Network Service Signaling Data Units with or without the use of logical signaling connections. Functions of the SCCP are also used for the transfer of circuit related and call related signaling information of the ISDN User Part with or without set-up of end-to-end logical connections (ITU-T recommendations Q.٧١٤, Q.٧٦٤) Circuit/ non circuit related signaling is view where SCCP services (connection less, connection oriented services, temporary signaling and permanent signaling connections) SCCP protocol classes, primitives, parameter & SCCP functional structure is describe in this chapter. SCCP message structure & type and SCCP addressing & routing are clarify by drawing & example s; finally this chapter is talk about signaling procedure & SCCP management The present high rate of introducing new telecom services will accelerate even more in the future. Many of these services will require fast and efficient transfer of signaling data between nodes in the signaling network. Some of the nodes will be databases with large

5 - ٥ - amounts of data and with different application programs, e.g. databases for cellular networks (VLR/HLR) and for handling IN services. The need for interchange of signaling data between such nodes was the driving force behind the idea of using the existing, SS٧ network as a bearer network for this communication instead of using dedicated data communication networks such as the PSPDN. The next step was to create SS٧ functions which were adapted for communication over the SS٧ network without having any relation to traffic channels (`circuits'), so called "noncircuit related signaling",. The first step in implementing functions capable of handling such communication was the creation of the SS No ٧ protocol SCCP. SCCP and MTP together make it possible to successively establish a communication path in the SS٧ network between, for instance, two databases. In the initial phase, the dialogue handling protocol between SS٧ and the application was created and implemented separately for each application. But economical and other factors prompted designers to create a general, standardized dialogue handling function in SS٧ which could work as an interface to different applications. A big number of applications are using databases to store information (e.g. Intelligent Network "In-services, mobile telephony services etc.). The communication of these applications with the databases has many thinks that are common to all of them. The TCAP can be said is representing this common protocol that is independent of each application. This is the background to the creation of a concept named Transaction Capabilities (TC) which provides general standardized protocol functions. TC reduces the need for development of new protocols whenever new features are introduced in telecommunication networks. Examples of applications that will use these Transaction Capabilities are: Mobile service applications. N-services like: Free phone (٨٠٠-service). Credit Card calling. Operation & Maintenance applications These users of the Transaction Capabilities are called TC-users.

6 - ٦ - Transaction Capabilities (TC) are defined in Recommendations Q.٧٧١ - Q.٧٧٥. TC provides the means to establish non-circuit-related communication between two nodes in the signaling network. The purpose and concept of TCAP is describe in the beginning of chapter sex, then transaction sub layer function and component sub layer function of dialogue handling (DHA) and component handling (CHA) is view. Finally the TCAP service primitives and message structure has been introduce in details. After the previous introduction we will start list and describe the basic building blocks in mobile system, the geographical mobile network structure and general traffic and signaling procedures. The function of mobile application part (MAP), application entities (AE) and application service element (ASE) is explained. Finally the signaling between MSC & BSC is view and follows by group of examples for traffic cases and procedures of setup call, attached, update location, roaming, handover and short message service traffic. The Intelligent Network (IN) is a set of resources that facilitates the speedy introduction of customized, competitive, advanced telecom services by operators without significant additional investment in the existing telephony infrastructure. IN resources include hardware and software. IN enables telecom operators to implement new services in reaction to and anticipation of competing services from other providers. IN separates the physical network from the systems used to deliver value-added services. Note that IN services were first designed for, and introduced in fixed telephony networks. In North America, IN is referred to as the Advanced Intelligent Network (AIN). To understand the IN services you need to learn about both GSM network structure and IN network structure, also you must know all protocol and standards of the IN. All the previous address will be describe in chapter eight. Public telephone systems today use the Internet for both; telephony voice and to carry signaling system ٧ (SS٧) messages. The Internet can provide reliable communication services by using the packet based transmission technologies used by IP-based protocols. There is a difference between the Internet and IP based networks. IP based networks uses Internet protocol to route information within the network.

7 - ٧ - The Internet is a public data network that interconnects private and government computers together. An IP based network does not have to be part of the Internet and it is possible for an Internet network operator to partition their data network to allow for different quality of service (QOS) levels. As a result, it is possible to reliably send SS٧ control messages over IP based networks that may be part of the public Internet. The Internet transfers data from point to point by packets that use Internet protocol (IP). Each transmitted packet in the Internet finds its way through the network switching through nodes (computers). Each node in the Internet forwards received packets to another location (another node) that is closer to its destination. Each node contains routing tables that provide packet forwarding information. These routing tables may be dynamically changed as a result of new connections or paths that may become available through the network. This is different than the SS٧ system that allows the operator to have more precise control over the routing tables. The use of IP based networks for voice, data, multimedia, and signaling offers new potential levels of network efficiency (utilization). A key protocol that has been developed to allow the sending of signaling control messages over IP based networks is Signaling Transport (SIGTRAN). The SIGTRAN protocol stack utilizes the Stream Control Transmission Protocol (SCTP). SCTP is an IP protocol that combines near-real time data transfer with reliable packet delivery and validation. To allow the use of protocols with SS٧ systems, several protocol adaptation layers have been created. These protocols adapt the message structures and flow of messages to emulate the message transfer parts (MTP) of the SS٧ protocol stack. Internet telephone systems are primarily composed of media gateways (MGs) and one or more media gateway controllers (MGCs). When Internet telephone systems interconnect to other networks such as the Public Switched Telephone Network (PSTN), they use signaling gateways (SG) or Network Gateways (NGWs). Some of the more common IP Telephony Systems include session initiated protocol (SIP), media gateway control protocol (MGCP), MEGACO, and ITU's H.٣٢٣ protocol. Once all the information regarding this proposes research project are collected, a simple and complete structure for signaling system can be build.

8 - ٨ - Therefore, a new application can be proposed and available (as in chapter ten). Those application is depend on how you can specify your location inside the GSM (global system mobile) network by generate a new SS٧ (signaling system no.٧) message I will call it location information message- include the information of the CGI (cell group identification), time advance and other information, then send this message to the HLR (home location register) database. So, later you will see how this information is useful to use by security department and by the vehicle owner to start, switch off, open, lock, break down and display the location of the vehicle on the electronic map which is fixed inside it; also it enables the security department to locate the place, direction and speed of vehicle inside the GSM network. Finally, deep description presentation is introducing with this thesis to allowing the reader to reach specific information in easy and short time ١-١-١ Call processing The most common application of SS٧ signaling is Call Processing which entails the transfer, between switches, of all information concerning the processing of the call. This includes the called and calling subscriber data. The charge number, call initiation and termination information, call hand-off information (intersystem when necessary). Etc. (Protocol: is a set of conventions governing the treatment and especially the formatting of data in an electronic communications system). ١-١-٢ Database Queries Another application supported by SS٧ signaling is the Database Query or interrogations directed to the various databases that exist within the network, e.g. HLR. VLR. EIR. AC. Etc (Discussed later). This signaling includes not only the interrogations, but also the return results to these interrogations, or queries. HLR Home Location Register VLR Visitor Location Register EIR Equipment Identity Register AC Authentication Center