Origination

Origination in VOIP telephony refers to calls that originate in the PSTN public switched telephone network and are carried to their destination over the Internet.

A VoIP call is initiated between two points, the initiation point is known as originator and the destination point is known as terminator.

An Internet Telephony Service Provider (ITSP) involved in the origination of telephone calls usually offers either or both of “PC to Phone calls” and “Phone to Phone calls”. The two major business models for VoIP Originator are “Prepaid” and “Postpaid”. Hardware requirements for VoIP origination are simple. The only hardware needed is a gateway that takes calls off the Internet and delivers them onto PSTN lines. All VoIP originators require a call termination arrangement with a terminator called VoIP terminator.

An ITSP (Internet Telephony Service Provider) involved in the origination of telephone calls usually offers either or both of:

• PC to Phone calls • Phone to Phone calls

The two major business models are:

• Prepaid • Postpaid

Hardware requirements for VoIP origination are simple. The only hardware needed is a gateway that takes calls off the Internet and delivers them onto PSTN lines. A gateway therefore has two types of Interfaces.

1. An Ethernet interface that connects the gateway to the Internet.

2. One or more telephony interfaces taking analog or digital phone lines.

An analog line can take one phone call at a time while a digital line can take more. A T1 line takes 24 calls and supports 1.5 Mbits while an E1 line takes 30 calls and supports 2Mbits simultaneously. A typical digital gateway has 4 T1s or 4 E1s

A gatekeeper is an application that receives the registration requests and calls from a dialer. When a user signs into the dialer, the request goes to the gatekeeper. The gatekeeper asks the Radius server to see if the username and password are correct and valid. The Radius server queries the database and sends a yes/no reply to the gatekeeper. If authenticated, the user can then make phone calls from the dialer. When the user dials a phone number in the dialer, the request again goes to the gatekeeper, gatekeeper again asks the Radius server if the user is allowed to make this call and has enough money to initiate it. The Radius server asks the billing server for the maximum duration of call that can be allowed to this user based on the amount of money remaining in his account or prepaid card. The billing solution looks up the destination of the call, finds the appropriate rate based on the peak/ off peak hours and the type of the customer and informs the Radius server exact duration in seconds that the user can call to this destination. The same info is returned by the Radius server to the gatekeeper and the gatekeeper informs the dialer the IP address of the destination gateway that can deliver the voice call to the destination. Given this information, the call is initiated if nothing else goes wrong and the two parties can talk. If they continue to talk until the maximum allowed duration of the call, the call is disconnected by the gatekeeper so the user doesn't consume any amount above the available limit.

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Wikipedia