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ENP Study Group Session #1 Telecommunications Operations BROUGHT TO YOU BY: THE FLORIDA NENA EDUCATION COMMITTEE.

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Presentation on theme: "ENP Study Group Session #1 Telecommunications Operations BROUGHT TO YOU BY: THE FLORIDA NENA EDUCATION COMMITTEE."— Presentation transcript:

1 ENP Study Group Session #1 Telecommunications Operations BROUGHT TO YOU BY: THE FLORIDA NENA EDUCATION COMMITTEE

2 Network Design and Architecture Transport Classifications InterLATA and Interexchange: A Local Access and Transport Area (LATA) is a specific geographic area where a local telephone service provider (TSP) may provide either local or long distance service. Interexchange carriers (IEC or IXC): Provide services to the public between local exchanges on an intra or interLATA basis. Local Exchange: A local exchange is a service area that is provided by an end office. The exchange area serves a geographic area in which charges and services are uniformed. A Local Exchange Carrier (LEC) provides telecommunications with a franchised area, within the same LATA. Local Loop: The wires that run from your home or business to your servicing central office. At the point the “loop” enters a resident a Network Interface Device (NID) is commonly use. In a business, is it referred to a point of demarcation (demar), usually found at a main distribution frame. The telecommunications provider is responsible for the service “to” the demar, the customer is responsible for getting the service “from” the demar.

3 Network Design and Architecture Traditional Telephone Switching Central Office (CO) is where a subscriber’s lines are joined to the telecommunications service provider (TSP) switching equipment so that connections can be made to other subscribers locally or over long distances. End Office or Class 5 Office is a switching system within a Local Access and Transport Area (LATA) It provides the connection of the customer’s equipment and delivers dial tone to the subscribers. The subscriber originates or receives communications from the network via the end office. Selective Router (also known as the E9-1-1 Tandem or Access Tandem) provides traffic concentration and distributes call between end offices or an interexchange carrier. A Selective Router provides interexchange carriers access to all end offices within the LATA. Facility or Facilities is a telephone company term that encompasses all the physical telephone plant that is required to provide service. This can include switching systems, cables, microwave and buildings. Facilities should be used for the physical plant, such as switching systems and buildings. Transport facilities would refer to the cables and microwave, etc. The basic function of a switching network is to provide communications paths from the calling party to the called party. If the calling party and the called party are in the same switching system, the call is an “intra-office call” If they are served by different switching systems, but within the same LATA, the call is considered intra-LATA. If the callers are served by different switching systems within different LATA’s, the call is considered to be an inter-LATA call. Networks are not engineered to allow all subscribers to place call simultaneously. Most systems are designed for a P01 grade of service. That means that 1 in every 100 call will receive a busy signal.

4 Network Design and Architecture Traditional Telephony Topology Central Office Tandem/ Access Tandem IEC LATA 1 LATA 2

5 Network Design and Architecture Transport Facilities (Transport Media) Transport Facilities: This refers to the physical medium over with the transmission take place. Copper Wire: This is the original infrastructure used by the telephone system, and there is still a lot of it in use today. This is common telephone wire that is found in cables in the form of pairs of wires twisted together. This is where the term “twisted pair” originated. Fiber Optics: This technology in where light is transmitter through thin filaments of glass. The light is turned off and on billions of times per second to represent binary signals. Fiber optics requires less space and is not sensitive to electromagnetic interference. Transmission over fiber is only digital. Microwave: This term is derived from the fact that the wavelength of the radio signal is being transmitted over a relatively short distance. Microwave uses electromagnetic waves in the radio frequency spectrum above 8990 Megahertz and below 20 Gigahertz to transmit facsimile, video, and data conversations. Satellite: This is a specialized form of microwave transmission where the “tower is in the sky”. Signals are sent and received by pointing a stationary dish antenna at the satellite. Coaxial Cable: This was developed to provide a more effective way to shield wires from outside electrical interference and radio signals. This cable can carry large quantities of information and is used to carry high speed data.

6 Network Design and Architecture Network Configurations Switching Configurations: Stand-Alone : This is a switch that is designed to serve a geographic area where the subcribers are within a defined loop length of a central office. A stand alone switch may also host one or more “remotes” Host/Remote: This is a switching technology that offers an economical way to telecommunications service providers to serve customers in remote areas. It allows for the host to be located in a central area, with remote switching units connected to it, but closer to the end customer. These are referred to a Remote Switching Units (RSU) or Remote Switching Modules (RSM). These units are connected to the host by an umbilical cable consisting of a data link and interconnecting trunks.

7 Network Design and Architecture Network Configurations Switching Configurations (Continued): Selective Routing: This is used to interconnect end offices when direct trunking is not economically justified or when alternate routing is justified. Selective Routers can perform some or all of the following functions: Interconnect end offices Connect to other selective routers Provide access to interexchange carriers (IECs) Provide access to operator positions. The following trunk types can be connected to a selective router: 2-wire, 4-wire, Analog, or Digital (SS7) Alternate Routing: Provides the routing capability for calls to a designated alternate location(s) if all the trunks are busy or out of service.

8 Network Design and Architecture Network Configurations Switching Architecture: Selective Router Architecture provided the intelligence of the system to be centralized in a single switch Central Office Selective Router PSAP A & ESN PSAP B

9 Network Design and Architecture Network Configurations Switching Architecture (continued): Ancillary features that are provided by the E9-1-1 Selective Router include: Selective Routing Selective Transfer Three –way Calling Speed Dialing Alternate Routing Default Routing Direct Trunking: With Basic systems, dedicated trunks go through the originating serving central office directly to the PSAP.

10 Network Design and Architecture Network Configurations Signaling/Transport: Transport and Signaling: Signaling is the sending and receiving of control information between the parts of a telecommunications network. Signaling that is circuit-associated uses metallic conductors to transmit signal and uses either in-band or out-of- band signaling. Centralized Automatic Message Accounting (CAMA): This was originally used for long distance billing. It is an arrangement that provides detailed call information at a centralized location. CAMA uses a switch at a central location to see as a hub to: 1. Collect Automatic Number Identification (ANI) information 2. Registers the call’s duration 3. Routes the call

11 Network Design and Architecture Network Configurations Signaling/Transport (continued): Multi-Frequency Signaling (MF) This is a type of address signaling in which ten decimal digits (the numbers on your touchtone phone) and five auxiliary signals are each represented by selecting a pair of frequencies out of the following group: 700, 900,1100, 1300,1500, and 1700 hertz (Hz). MF pulsing system consists of transmitting and receiving equipment for sending frequency combinations in the voice band. Dual Tone Multi-frequency (DTMF) also referred to as “Touch Tone Dialing” also uses a combination of two specific tones to represent a digit or other character in which eight tones are paired. Touch tone and DTMF are NOT the same thing. Both use a combination of 2 specific tones to represent a digit or other character, but the tones are different.

12 Network Design and Architecture Network Configurations Transmission Systems: Switch Types: Analog: Analog signaling uses a signal that may be variable in amplitude (amplitude modulation of “AM”) or frequency (frequency modulation or “FM”. Digital: Digital switching converts the analog signal to digital and this binary encoded information is routed between an input and an output port by means of time division multiplexing (TDM) rather than using a dedicated circuit. Packet: This technology used in the next generation network transmit a caller’s voice using Voice Over Internet Protocol (VOIP) on a variety of different data transport.

13 Network Design and Architecture Types and Features of Systems Basic 9-1-1: The caller could dial and the TSP’s end office would be programed to send all calls to a single destination, regardless if that PSAP provided services to that caller’s area. In the beginning it also did not provide the caller’s telephone number. Basic with ANI and ALI: Service providers started using CAMA to facilitate the delivery of the caller’s telephone number to the PSAP. Since the telephone companies stored the subscriber’s data based on telephone numbers, they would also be able to provide the name and address. This system only provides ANI and ALI and is NOT Enhanced because there is no selective routing. (HINT What feature must you have to be considered an Enhanced system?) Basic with Multiple End Offices (Single E9-1-1 Selective Router): In this configuration multiple end offices to a PSAP are connected to a selective router office, and from that selective router a single trunk group is connected to a PSAP.

14 Network Design and Architecture Types and Features of Systems Enhanced 9-1-1: Enhanced is separated from Basic by Selective Routing. Selective Routing allows a call to be delivered to a specific PSAP based upon the street address of the caller. Enhanced requires three additional components from Basic 9-1-1: 1. A Master Street Address Guide (MSAG) 2. The translation of the caller’s address to an Emergency Service Number (ESN). 3. A Selective Routing Database (SRDB) associated with the E9-1-1 Selective Router that has the ability to translate the Telephone number (TN) to an ESN. Emergency Service Zones (ESZ) are a geographic zone served by one particular combination of Police, Fire, and EMS. Each ESZ contains the set of street addresses served by that combination of PD, FD, and EMS. The ESZs are then assigned an ESN, that the E9-1-1 Selective Router can use for Selective Routing. In the MSAG, all address ranges that fall within a specific ESZ are identified and assigned an ESN. The Database Management System then identified all of the telephone numbers at those asdresses and assigns the ESN to the customer’s records.

15 Network Design and Architecture PBX E9-1-1 Interconnection Private Branch Exchanges (PBX) are used in businesses with a single location, a campus environment containing multiple buildings or a distributed architecture where satellite locations are geographically remote from the host PBX. An issue in the US in that less than half of the states of regulations that cover the delivery of emergency calls and the obtaining the location of the caller behind that PBX. This is know as Multi-Line Telephone Systems (MLTS). PBX Using Main Telephone Number: Normally, when someone calls from a station off a PBX, the main listed telephone number and address of the main location will display at the PSAP. The actual location of the caller originating the call can be anywhere in the building or in other buildings served by the PBX. PBX Using Private Switch ALI (PS/ALI): This service allows the PBX owner to recreate and maintain ALI records that identify each station address or Emergency Response Location (ERL) which may represent the location of multiple stations. The records are uploaded to the Database Management System database. The owner of the PBX is responsible for the creation and maintenance of these records. There are 2 types of network connections that can be used to establish the call process. Newer PBX’s can use a Primary Rate ISDN connection. The calls enter the selective router over the regular dedicated end office Emergency Service (ES) trunks. Older PBXs need to install an adjunct unit that uses dedicated trunks that will connect the PBX either directly to the E9-1-1 Selective Router or in some cases the end office.

16 Network Design and Architecture PBX E9-1-1 Interconnection Host PBX with Satellite PBXs: This configuration may be used when a large multiregional corporation uses a host and one or more satellite PBXs. In this case there satellite PBX could be located in another jurisdiction. If the corporation has PS/ALI, the callers information will route to the correct location. VoIP PBX Replacement/IP PBX: VoIP technology has replaced circuit switching for enterprise PBX systems. While this is newer technology, it still has the same limitations as a conventional PBX. An option that is available to an enterprise VoIP system is to use the same infrastructure deployed to support VoIP Service Providers (VSP) This system uses the VoIP Positioning Center (VPC) to route calls and deliver ALI for the VoIP callers.


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