This blog post will explain what SIP termination and origination are. They are two similar services, but they are responsible for different directions of the call flow. Termination handles outgoing calls delivered by an SIP trunk. Origination handles incoming calls to a direct dial phone number. Termination means sending phone calls from one internet telephony service provider to another. SIP trunking is used to send the outgoing call to another provider. An SIP trunk connects a device to the Internet while a direct dial number identifies the device. Features included with termination are caller id management, flexible routing, call waiting, and voicemail. Most termination providers have an administration panel that allow a user to determine and configure what services that are needed. It is a cost-effective solution that is cheaper than public switched telephone network phone lines. The need to spend money on hardware and maintaining it is eliminated. Origination is a form of inbound call handling that involves sending incoming calls to a destination on a PBX. Users on a PBX need their extension configured to use a direct dial number to use origination service. Routing calls to a PBX is enabled with SIP origination. The PBX enables SIP origination by managing incoming calls and sending them to the correct destination. Inbound routes can be configured to determine where the call is originated to. CID information from the caller or the number that was dialed by the caller are used to determine an inbound route. There are two ways to route calls to a PBX. Host based routing and SIP registration. SIP registration authenticates a SIP device to communicate with a SIP server. Host based routing allows calls to be directed to a specific PBX based on a callers IP address or domain name. There are other features on a PBX that can be used with a direct dial number. Those include ring groups, interactive voice response systems, and announcements. Someone will dial a direct dial number that is attached to an extension on a PBX. An internet telephony service provider receives that call and routes it to an extension on a PBX. Adding and removing direct dial numbers from an origination provider is easy. Existing Internet infrastructure within a company allows a user to use origination service without them having their own Internet connection. Calls can be monitored by a company to determine what business strategies they need to use.