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

Calling party

The calling party is a person who initiates a telephone call over the public switched telephone network, usually by dialing a telephone number....

 on a telephone exchange

Telephone exchange

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...

 of PSTN, and handing off the calls to a VoIP endpoint or to another exchange or telephone company

Telephone company

A telephone company is a service provider of telecommunications services such as telephony and data communications access. Many were at one time nationalized or state-regulated monopolies...

 for completion to a 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....

.

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

Call termination

Call termination, also known as voice termination, refers to the routing of telephone calls from one telephone company, also known as a carrier or provider, to another.The terminating point is the called party or end point...

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

The term is often used in referring to a VoIP trunking

Trunking

In modern communications, trunking is a concept by which a communications system can provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of...

service.