Voice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.

Internet telephony refers to communications services — voice, facsimile, and/or voice-messaging applications — that are transported via the Internet, rather than the public switched telephone network (PSTN). The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression/translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end.[1]


VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. Codec use is varied between different implementations of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.

The preceding 15 years have seen mammoth steps to the fore in the styles of presented communication equipment.
To help you get to grips with this equipment the subsequent commercial telephone systems guide has been put together, and to make the it easy to figure out the phone system types have been written down in date order of there launch to the market.

Digital PBX Systems
This type of communications platform, also badged a key system or TDM switch have been in circulation for nearly 20 years but are still built today in much smaller numbers. A digital PBX is put in locally on the company premises themselves and all phone calls are dealt with on site, both inbound and outbound.

Feature Line telephone Solution
Feature line, or Centrex, solutions have been around for over 20 years and are provided by the telephone commercial line carriers themselves. A devoted telephone line is installed for every user that wants a phone. The phone calls are processed off site at the local phone exchange and the service is usually installed today for minor set ups.

Hybrid PBX Solutions
The most familiar business phone system solution in operation today is a Hybrid PBX which supports both IP and digital phone lines and equally IP and digital handsets. Hybrid PBX phone systems are put in and managed locally in the users business building.

IP PBX phone System
An IP PBX telephone solution, frequently referred to as a pure IP system, provides simply IP compatible end points. The IP devices will consist of the telephone lines themselves and actual telephone extensions. IP PBX phone solutions are also installed into the owners company premises with calls traffic switched on site.

Hosted PBX
A Hosted PBX small business solution, otherwise known as IP Centrex or hosted VoIP system, circles around end users running an IP enabled commercial telephones on their work stations which in turn are installed via data circuits to a remotely hosted telephone system, regularly housed in a dependable data centre. Calls are processed off site.

Soft Switch telephone Systems
A soft switch telephone system is fundamentally just telephone based software that is uploaded onto a PC server, normally hosted by the local business. This system supports SIP based phones, and is progressively more connected to SIP trunks to allow outbound and inbound calls as oppose to traditional ISDN or PSTN phone lines.

Mobile PBX commercial phone Solution
Mobile PBX or Hosted MBX telephone system acts as a remotely hosted PBX with all calls dealt with off site, however instead of using fixed IP telephone handsets mobile telephone handsets are connected to handle all telephone calls. On site phone system operators often connect a headset and Computer to deal with the incoming calls.