What is an IP PBX?

A PBX is a customer premises telephone system that manages telephones in the enterprise and acts as the gateway to external voice networks. A switch/router directs incoming packets to the appropriate data network. Traditionally, two separate networks are required: one for voice and one for data.

Instead of two separate networks, one each for data and voice, only one network is needed if voice is packetized (Voice over IP) and sent over the data network.

An IP PBX is a combination of a switch/router and a PBX that handles Voice over IP (VoIP):

In an IP PBX, computers and telephones can be on a shared LAN that is connected to the IP PBX.

An IP PBX also acts as a gateway that provides voice connections (voice lines, T1s) to a ITSPs, Internet Telephony Service Providers, etc. and data connections (cable, DSL, ISDN, E1) to a cable operator, an ISP, etc. IP PBXs can be used bypass the circuit-switched telephone network by using the data network to connect to branch offices and other locations on the data network.

Using a single converged network that carries both voice (packetized) and data allows development of new services not typically available on the traditional network - for example, the use of one central directory across multiple locations and unified messaging.

An IP PBX replaces a traditional PBX. It can be used with

• an IP phones (with a built-in DSP chip that converts voices to IP packets and vice versa),
• a soft phone (software application on PCs that also converts voice to packets and vice versa), which is used with a headset or a handset,
• existing phones using adapters that packetize voice,

What are the Advantages of an IP PBX?

• handles both voice and data,
• is cheaper since it requires only one network to install and maintain instead of two,
• saves on line rental as only one adsl connection is required over one telephone line (this can support up to 4 conversations per 64k bandwidth),
• reduces equipment costs (only IP based products; no voice products needed),
• reduces phone call charges, inter-branch office calls are free(by using the data network),
• is easier to provision (just plug in from wherever),
• supports services such as unified messaging,
• is more flexible,
• is more scalable,
• makes it easier to provide new services, such as data and video collaboration,
• allows remote configuration (over the Web), and
• supports modular software upgrades, new technologies (new CPUs, etc.) are easy to incorporate.

Where will an IP PBX be used and can they be used in a hybrid setup with digital or analogue PBX?

IP PBXs are good candidates for any business wishing to save money and embrace new technology.