The calling party is a person who (or device that) initiates a telephone call

Telephone call

A telephone call is a connection over a telephone network between the calling party and the called party.-Information transmission:A telephone call may carry ordinary voice transmission using a telephone, data transmission when the calling party and called party are using modems, or facsimile...

 over the public switched telephone network

Public switched telephone network

The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...

, usually by dialing a telephone number

Telephone number

A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...

.

Or a person originating an exchange of information between two amateur radios

Amateur radio station

An amateur radio station is an installation designed to provide radiocommunications in the amateur radio service for an amateur radio operator. Radio amateurs build and operate several types of amateur radio stations, including fixed ground stations, mobile stations, space stations, and temporary...

. The process is called call origination

Call origination

Call Origination, also known as voice origination, refers to the collecting of the calls initiated by a calling party on a telephone exchange of PSTN, and handing off the calls to a VoIP endpoint or to another exchange or telephone company for completion to a called party.In the VoIP world , the...

 and the person who (or device that) answers the call is the called party

Called party

The called party is a person who answers a telephone call. The person who initiates a telephone call is the calling party....

.

The calling party is usually the party that pays the fee, if not free, for placing the call, however in reverse charge (or collect

Collect call

A collect call in the USA and Canada or reverse charge call in the UK and other countries is a telephone call in which the calling party wants to place a call at the called party's expense...

) calls this may not be the case.

While roaming

Roaming

In wireless telecommunications, roaming is a general term referring to the extension of connectivity service in a location that is different from the home location where the service was registered. Roaming ensures that the wireless device is kept connected to the network, without losing the...

 on an international network using a mobile phone

Mobile phone

A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...

, the calling party may need to pay an extra fee for the subsequent use of the overseas network.

Human call originator

In some countries, it is common etiquette

Etiquette

Etiquette is a code of behavior that delineates expectations for social behavior according to contemporary conventional norms within a society, social class, or group...

 for a call originator to identify himself first instead of the receiver, when the connection is established.

Machine call originator

Modem

Modem

A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...

s and fax machines use different tones when originating or answering a connection, which may be a source of problem for the user.