V1 Flashcards
(32 cards)
Any circuit provided by a telecommunication service provider is made up of three components:
access, network connection and billing agreement.
The commercial organizations that offer services of access, network connection and billing agreement are often called…
carriers or common carriers because they carry many users’ traffic over a common facility.
Access circuits are…
physical lines with circuit terminating equipment at each end. These circuits run from a user’s site to the nearest physical attachment point into the common carrier’s network.
The location containing this physical attachment point is usually called…
a Central Office (CO). It might be pulled through the CO to another company’s Point of Presence (POP) to get access to that other company’s network.
The access network is…
the totality of the physical equipment used to link the user to a Central Office (CO). This is often also called the outside plant.
Switches are…
devices that connect one circuit to another for the duration of a communication session.
Switching centers are…
the buildings that contain switches.
Transmission network is…
the term used to generally refer to the systems that connect the COs.
POTS
Plain Ordinary Telephone Service
A CO switch connects a user’s loop to a particular inter-office circuit to make an end-to-end communication path for the duration of a phone call, and then releases it so someone else can use that inter-office circuit. This technique of establishing end-to-end communications across a network is called…
circuit-switching. It is sometimes also referred to as dial-up.
The transmission network…
connects switches, multiplexers and routers in a Central Office to similar equipment in other switching centers. This includes direct connections between COs within a city and connections for long-distance communications.
Connections between switches are called…
runks; a trunk carries one telephone call. For the most part, trunks are not individual circuits, but instead are carried on fiber-optic based trunk carrier systems.
Since everything is carried together, redundant connections must be made between COs and other switching centers to protect against cut lines. The most cost-effective way of doing this is to connect switching centers together neighbour-to-neighbour to form…
rings.
SONET
Synchronous optical networking
When, where and by whom was a telephone invented?
Alexander Graham Bell in Brantford, near Toronto, Canada in 1874
Historical pattern of telephone system development
Development of a monopoly on providing telephone service, either owned by the government or regulated by the government; then break-up of this monopoly and introduction of competition in connecting the pieces; and finally competition within the pieces.
PSTN
Public Switched Telephone Network
The telephone is located in a building called…
and the telephone switch is located in a building called…
a Customer Premise (CP)
a Central Office (CO).
The telephone is connected to the telephone switch with…
two copper wires, often called a local loop or a subscriber loop, or simply a loop. This a dedicated access circuit from the customer premise into the network.
Copper is a good conductor of electricity - but not perfect:
it has some resistance to the flow of electricity through it. Because of this, the signals on the loop diminish in intensity or attenuate with distance.
The maximum resistance allowed is usually
1300 ohms, which works out to about 18,000 feet or 18 kft, which is 3 miles or 5 km on standard-thickness 26-gauge cable but could be as long as 14 miles or 22 km on thicker 19 gauge cable.
Thus, COs traditionally had a serving area of about three miles radius around them, about…
27 square miles or 75 km2.
With suburban sprawl, we cannot build COs every five miles, so in practice, new subdivisions are served from…
remote switches, which are low-capacity switches in small huts or underground controlled environment vaults. The remote provides telephone service locally on the loops in the subdivision. The remote and the loops are connected back to the nearest CO via a loop carrier system that uses fiber or radio.
Telephone switches are connected with…
trunks.
