The calling party (also called caller, call originator or A-party) is a person who (or device that) initiates a telephone call over the public switched telephone network, usually by dialing a telephone number. The process is called call origination and the person who (or device that) answers a telephone call is the called party.

The calling party is usually the party that pays the fee for placing the call, however in reverse charge (or collect) calls this may not be the case.

While roaming on an international network using a mobile phone, the calling party may need to pay an extra fee for the subsequent use of the overseas network.