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What is IP PBX?

PBX (Private Branch Exchange) is the foundation of the business telephony system. It switches calls between VoIP (Voice over Internet Protocol or IP) users on local lines while allowing all users to share a certain number of external phone lines. The typical IP PBX can also switch calls between a VoIP user and a traditional telephone user, or between two traditional telephone users in the same way that a conventional PBX does. IP PBX is based on IP telephony (IPT), which uses standard packet-switch protocols to carry voice traffic across a data network. IPT brings together a set of convergence technologies that lets PBX vendors combine voice with web, video, and email, and integrate this multimedia platform with business productivity applications. Using IPT, enterprises can achieve a unified collaborative communications network connecting a geographically dispersed community, irrespective of locality and mobility.

The Advantages

- Customers are more in control

- IP-PBX systems provide PBX functionality such as call holding, conference calling, and auto attendant over IP-based networks instead of traditional circuit-switched networks. From a technology perspective, an IP PBX is a telephone switch that supports VoIP by converting IP phone calls into TDM connections for the PSTN. Many IP PBXs also support hybrid environments, allowing businesses to route analog and digital calls as well.

- IP PBX use of open source technology, such as Asterisk, that reduce the cost of network and systems management, as well as the legacy PBX problem of vendor lock-in. IP PBX also uses the IP network to receive and send voice traffic, the same network used for data. Reduced tolls can also be a benefit for companies making lots of international calls. Many businesses also cite improved conferencing features at greatly reduced costs.

There are different types of configuration.

IP PBX Architecture Configurations: Depending on specific communication requirements, an enterprise may employ one of these IP PBX configurations.

Client-Server Configuration: A client-server IP PBX (sometimes referred to as Pure IP PBX) supports client devices and switching using only IP telephony. Connectivity to traditional PBX servers or the PSTN is accomplished using an external TDM-to-IP gateway. Such a solution is ideal for new businesses or for branch offices.

Converged Configuration: A converged IP PBX supports both VoIP and TDM in the same server. It connects to PSTN and IP data networks and supports legacy client devices, as well as IPT stations such as IP phones, SIP phones, and soft phones.

Hosted Configuration: Hosted IP solutions may take the form of a media gateway that provides an IP dial tone to the customer premises equipment (CPE), or a full-scale applications server that provides a suite of PBX services using IPT. Hosted configurations support higher densities than CPE solutions as well as carrier-grade requirements for high availability and reliability.

By San Singhania