The gateway directs some incoming calls to the legacy PBX and others to the IP PBX. The new IP PBX is integrated over a VoIP protocol (generally SIP).
Another interface connects to the trunk port on the legacy PBX. In this case, the PSTN trunks are connected to one interface on the gateway. Other uses for VoIP gateways include staged migrations, where the gateway acts as a bridge between the PSTN, a legacy PBX and a new IP PBX. In the event of a failure on the primary, the gateway can communicate with a backup system. The gateway normally communicates with a primary IP PBX. It also makes it easy to build redundant systems. Using a gateway to connect a VoIP phone system to traditional phone lines makes sense in situations where SIP trunks are not available or where your application requires the reliability of the PSTN. Calls coming from VoIP sources are converted into the appropriate legacy protocol and delivered to the PBX. Calls from the PBX to the outside world are converted into VoIP calls and sent over the Internet to a VoIP service provider or other VoIP peers. The PBX sees the gateway as either the phone company or as another networked PBX. The gateway connects to the legacy system through either analog or digital trunk ports. Gateways are typically used to connect legacy phone systems (PBXs or ACDs) with VoIP resources, or to connect modern VoIP phone systems with legacy phone lines.Īdding VoIP to a legacy PBX system is a great way to add features and reduce costs. A VoIP gateway is used to build a bridge between the worlds of legacy telephony and the VoIP.