Telecom Terms and Concepts Introduction to terms

Telecom and Computers are merged to deliver data Tele – distance Communications Transfer of information from a transmitter to a receiver

Many parts come together to provide a path

Some terms to know Transmitter Receiver Circuit Link Line Trunk Channel Switch Network

Transmitter Also known as sender or source Originates the information transfer Samples include: – Voice telephones – Data terminals – Host systems – Video cameras

Receiver Also known as the sink Destination of the information transfer Samples include: -Telephones -Host computers -Video Monitors

Circuit A communications path, over an established medium, between two or more points, from end to end, between transmitter and receiver Generally implies a logical connection over a physical path May be for transport or access

Access Circuits From customer premise to the edge of the carrier network

Transport Circuit Employed at the core of the network for long- haul transmission

Some types of Circuits Simplex – (one way) Half-duplex – (two way, but only one at a time) Full-duplex – (two way, at the same time)

Link A two-point segment of an end-to-end circuit (e.g., from a terminal to switch) Circuits generally consist of several links

Line Several definitions can make this term confusing. PBX – station line – connection between the PBX switch and the station users terminal equipment Rate and Tariff (Telco) – line refers to the local loop connection from Telco CO (Central Office) to the user in support of CPE (Customer Premise Equipment)

Lines in Telco-speak Examples – Single phone line to a business – A multi-line set Usually voice grade – although this is changing as the infrastructure matures For Telco’s the line side is the users access to the network – for the other side there are Trunks

Trunk A communications circuit, available to share among multiple users, on a pooled basis with contention managed by an intelligent switching device. – NOTE: this is not the same switching device as in a Local Area Network – i.e. Layer 2

Trunks Connect Switches Tie Trunks – connect PBX switches in a private, leased line network Central Office Exchange Trunks – connect PBX’s to Telco switches Interoffice Trunks – Connect CO Exchange groups

Trunk Groups Groups of trunks serving the same special purpose. – WATS (Wide Area Telecommunications Service – DID (Direct Inward Dial)

Trunks are Directional One way out -- Originating One way in -- Terminating Two-way – Combination

Channel A means of communication between transmitter and receiver A logical connection over a physical circuit to support a conversation

Switch Establishes, maintains and changes logical connections over physical circuits – Circuit – Packet – Frame – Cell

Edge Switches Positioned at the edge of the network Users gain access via an access link

Core Switches Also known as Tandem Switches High capacity switches at the core to interconnect edge switches

Network The fabric of elements which work together to support the transfer of information