telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than tha ...

, a toll switching trunk or toll connecting trunk is a

trunk Trunk may refer to: Biology * Trunk (anatomy), synonym for torso * Trunk (botany), a tree's central superstructure * Trunk of corpus callosum, in neuroanatomy * Elephant trunk, the proboscis of an elephant Computing * Trunk (software), in rev ...

connecting an

end office {{No footnotes, date=August 2008 A class-5 telephone switch is a telephone exchange in the public switched telephone network (PSTN) that directly serves subscribers and manages subscriber calling features. Class-5 services include basic dial-tone, ...

to a toll center as the first stage of concentration for intertoll or long-distance traffic.

Operator assistance Operator assistance refers to a telephone call in which the calling party requires an operator to provide some form of assistance in completing the call. This may include telephone calls made from pay phones, calls placed station-to-station, p ...

or participation may be an optional function. In U.S.

common carrier A common carrier in common law countries (corresponding to a public carrier in some civil law systems,Encyclopædia Britannica CD 2000 "Civil-law public carrier" from "carriage of goods" usually called simply a ''carrier'') is a person or company ...

telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...

service, a toll center designated ''Class 4C'' is an office where assistance in completing incoming calls is provided in addition to other traffic; a toll center designated ''Class 4P'' is an office where operators handle only outbound calls, or where switching is performed without

operator assistance Operator assistance refers to a telephone call in which the calling party requires an operator to provide some form of assistance in completing the call. This may include telephone calls made from pay phones, calls placed station-to-station, p ...

References

See also