Call Origination

Call origination, also known as voice origination, refers to the collecting of the calls initiated by a

calling party The calling party (in some contexts called the "A-Number") is a person who (or device that) initiates a telephone call. The person who, or device that, receives a telephone call is the called party (or callee or B-party). In some countries, it ...

on a

telephone exchange telephone exchange, telephone switch, or central office is a telecommunications system used in the public switched telephone network (PSTN) or in large enterprises. It interconnects telephone subscriber lines or virtual circuits of digital syste ...

of the

PSTN The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local teleph ...

, and handing off the calls to a

VoIP Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet ...

endpoint or to another exchange or

telephone company A telephone company, also known as a telco, telephone service provider, or telecommunications operator, is a kind of communications service provider (CSP), more precisely a telecommunications service provider (TSP), that provides telecommunicat ...

for completion to a

called party The called party (in some contexts called the "B-Number") is a person who (or device that) answers a telephone call. The person who (or device that) initiates a telephone call is the calling party. In some situations, the called party may number m ...

. In the VoIP world, the opposite of call origination is

call termination Call or Calls may refer to: Arts, entertainment, and media Games * Call, a type of betting in poker * Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage Music and dance * Call (band), from Lahore, Pak ...

, where a call initiated as a VoIP call is terminated to the

. The term is often used in referring to a VoIP trunking service that provides the ability for calls to originate on the PSTN and be delivered to a customer's VoIP endpoint. It is often referred to as "DID" (for

Direct Inward Dialing Direct inward dialing (DID), also called direct dial-in (DDI) in Europe and Oceania, is a telecommunication service offered by telephone companies to subscribers who operate a private branch exchange (PBX) system. The feature provides service for ...

) which more properly refers to a service entirely within the PSTN where individual PSTN numbers can terminate on a customer's PBX. {{telecommunications-stub Voice over IP Teletraffic