VoIP PBX or IP PBX (Internet Protocol Private Branch Exchange) is a telephony system that makes use of IP data networks to facilitate telecommunication. The immediate advantage of VoIP PBX is that enterprises using it need not have to replace their existing phones or phone numbers to accommodate the new VoIP facility. It is a robust technology that works in tandem with the existing communication infrastructures. In other words, the VoIP technology can use the existing PSTN lines via the VoIP gateway, and there is no much of additional infrastructure involved in its entire installation.

How does a VoIP PBX work?

The basic architecture of an IP PBX system consists of an IP PBX server, one or more SIP phones or VoIP phones, and a VoIP gateway, as mentioned already, to connect to the existing PSTN lines (optional though). The IP PBX server functions quite similar to a proxy server. The SIP or VoIP phones, which can be either hardware phones or soft phones, has to register with the IP PBX server, and when they wish to make a call to another phone ? a VoIP or SIP phone ? actually a request is send to the IP PBX server to establish the connection. The IP PBX server will have a directory of all users/phones and their respective SIP addresses, and using this info, it could connect an internal call or route an external call via a VoIP service provider or a VoIP gateway, whichever is applicable. The process is just quick and simple.

So, what are the advantages of VoIP PBX over conventional PBX systems?

The most important plus of VoIP PBX is that it is many times easier to install and configure than a traditional phone system. Any one who knows the basics of computer and networking can install the IP PBX in a PC and maintain it reasonably well. Also, since it is all software, there is no complex wiring involved anywhere. If somebody wants to connect a hardware phone to an IP PBX system, he/she can directly plug it into a standard network port (soft phones can be installed directly into the PC). This must be read in the backdrop of the fact that in the case of proprietary phones, only a trained technician could handle its installation, configuration, wiring, and overall maintenance.

Another big advantage of IP PBX is its low cost of operation. Since the calls make use of IP networks, even long distance international calls are many times cheaper. If the call is made between the phone systems that links the branches of enterprises, it is absolutely free of cost. Further, since IP PBX is built on an open SIP standard, users can use any SIP software/hardware phone with virtually any SIP based PSTN Gateway, IP PBX or VoIP provider. There is no question of a vendor lock-in in any circumstance.

Yet another positive with IP PBX is that it could easily handle any number of additional phone connections and extensions without disturbing the efficiency of the network. This is in deep contrast to the conventional phone systems, which might require additional hardware modules to accommodate the newer connections and extensions.

Finally, with VoIP PBX, it facilitates hot desking and roaming, provides easy usability, and better manageability via the IP PBX Windows client. With proprietary phones, in order to implement the latter feature, it might require expensive hardware components.