A VoIP gateway (or PSTN Gateway) is a device which converts telephony traffic into IP for transmission over a data network. They are used in two ways:
1. To Convert Incoming PSTN / Telephone Lines to VoIP/SIP:
In this manner the VoIP gateway allows calls to be received & placed on the regular telephony network. In many business cases, it is preferable to continue to use traditional phone lines because one can guarantee a higher call quality and availability.
2. To Connect a Traditional PBX / Phone System to the IP Network:
In this manner the VoIP gateway allows calls to be made via VoIP. Calls can then be placed via a VoIP service provider, or in the case of a company with multiple offices, inter office calls costs can be reduced by routing the calls via the Internet. VoIP gateways are available as external units or as PCI cards. The vast majority of devices are external units. A VoIP gateway will have a connector for the IP network and one or more ports to connect the phone lines to it.
Types of VoIP Gateways
1. Analog units: Analog units are used to connect regular analog phone lines to the gateway. Analog units are available for between 2-24 lines.
2. Digital units: Digital units allow you to connect digital lines either one or more BRI ISDN lines (Europe), one or more PRI/E1 lines (Europe) or one or more T1 lines (USA).
