The Telephone Network Chapter 3 Basic Call Processing Call Request Call Accepted Conversation Starts TALKING Time Call Termination Global Telephone Network Local Exchg sw Digital Loop Carrier Satellite Global Telephone Network Radio Links United States Microwave Trunk 832 Local Exchange (Exchange Switch) Trunk Relay Tower Trunk Local Exchange (Exchange Switch) DLC (Digital Loop Carrier) Twisted Pair 860-832-2321 Main Switch Telephone RJ-11 (Telephone Socket) 860-832-2941 Fax 860-832-2321 Undersea Fiber v v International Exchange Across the oceasn v Main Exchange 860 T1/Twisted Pair v v International Exchange Exchange Local Switch Exchange Tandem Sw Int. Exchg SW Germany Network Basics Components Technology: type of the circuit established on the trunk Analog: FDM Digital: TDM, T-Carriers Basic Switching technology Trunk: connection between central offices Local Office/Switch: Receives and route call requests; connected to the customer Tandem Office/Switch: Receives and routes call requests; connected to another office Digital (TDM based) / Analog Routing: can be Intra or Inter-company To a customer on the same switch To another tandem switch T-Carrier Trunks Basic Call Routing Tandem Office The local switch can route the request three different ways: Customer (Intra/Inter Company) Shared Trunk Exchange Switch 214-403-4433 Local Office Local Office Customer Tandem Switch Customer Local Switch Definitions Tandem Switch Trunk Local Exchange Carrier ILEC Local Access Transport Area 161 LATA have been defined covering the US, 1981 Different companies can have point of present (POP) in different LATAs LEC Connection between two offices - a trunk is often shared between multiple users LATA An intermediary switch connected to another switch Incumbent Local Exchange Carrier Refers to 7 RBOCs companies CLEC Competitive Local Exchange Carrier More Definitions Telco FG-D short form for telephone company. Sometimes it means a local telephone company, such as a Bell operating company or an independent local telephone company. Featured Group D - A protocol which defines interconnection rules between a local exchange carrier (LEC) and an inter-exchange carrier (IEC) such as MCI or Sprint. Also known as equal access because it guarantees that all carriers are processed equally. It is also referred to the trunk connection Inter-exchange carrier (IEC or IXC) A telephone company that provides connections between local exchanges in different geographic areas. They're commonly referred to as "long-distance carriers." IXCs include AT&T, MCI, Sprint, and others. Inter-Company Routing Tandem Switch Tandem Long Distance DLC: Digital Loop Carrier – multiplexing channels Shared Trunk POT: Plane OLD Telephone/ Or Point of Termination End office Switch All wires belong to ILEC ILEC CLEC DLC POT u Long Distance Routing Different LATA/Diff. Company Trunk ILEC DLC u Toll/ Tandem SW Featured Group D Trunk IXC LD SW Tandem Long Distance Network Inter-exchange Long Distance SW IXC LD SW Local Office IXC: Inter Exchange Carrier – must have a point of presence in LATA IMT (DS3/SONET) IMT: Inter Machine Trunks provided by IXC Long Distance Routing Different LATA/Diff. Company Trunk ILEC DLC u Toll/ Tandem SW Featured Group D Trunk IXC LD SW Tandem Int/LD Distance Network Inter-exchange Long Distance SW IXC LD SW Local Office IXC: Inter Exchange Carrier – must have a point of presence in LATA IMT (DS3/SONET) IMT: Inter Machine Trunks provided by IXC Long Distance Calls A +1 indicates that the call is going to the tandem switch – long distance call Sometimes a code is used to indicate the long distance company: 1323 +1 +area code +local number MCI Avoided due to equal access law using they use Featured Group D Trunks Featured Group D (FG-D) The FG-D protocol defines interconnection rules between a local exchange carrier (LEC) and an interexchange carrier (IEC) such as MCI or Sprint. Long Distance (international) Calls IMT Inter-exchange Office Inter-exchange Office Tandem Office Tandem Office Local Office Local Office DLC DLC POT Inter Machine Trunks POT Putting it all together…. Overseas Switch POP POP Switch Switch Switch POP POP Switch POP Routing is a major issue! POP Switched access provided by LEC (DS3) Inter Machine Trunks provided by IXC (DS3/SONET) Inter Machine Trunks connecting switches (DS3/SONET) Some interesting stuff! 24 hour period - calls per minute recorded at an IXC switch 2,000 1,800 Calls per minute 1,600 1,400 1,200 1,000 800 600 400 200 0 0:00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 Busy hour - calls per minute recorded at an IXC switch 2,000 Calls per minute 1,800 1,600 1,400 1,200 1,000 800 600 400 200 0 10:30 10:45 11:00 11:15 11:30