The categories of business telephone systems can be broadly divided in to three: KSU-Less phones, Private Branch Exchange (PBX) systems and Key systems. Your choice of system will depend on your requirement of extensions and the features that your phone will need.
Most companies having less manpower will find the KSU-Less systems very suitable for themselves. You may require certain additional features that are available only on Key phone systems or PBX.
A KSU-Less system requires a very less investment and includes almost all that are usually available on the small business telephone system. An advantage of the KSU-Less system is that it is easy to unplug or relocate. This is because this system is not permanently wired into the office premises. Another thing that you have to look for is the compatibility of the system with the accessories, including headsets, answering machines, modems and fax machines.
Private Branch Exchange (PBX) Systems
The PBX system is to be used if you typically have a requirement of 40 extensions or you need your business telephone system to have advanced functions. PBX systems are expensive and can usually be afforded by multinational corporations. These corporations generally need more extensions within the same business structure and the PBX systems suit their need and their type of work.
A key system is typically used in organisations that have a requirement of around 5-40 extensions. The main feature of a key system is that it provides a function wherein a call can be made from one extension to another extension in the same premises without the trouble of someone else picking up the line that is being used. However, these features are not available on ordinary phones. A key system is usually less flexible compared to a PBX system.
PBX Systems (hybrids)
Nowadays the business telephone systems available offer best of both worlds. Key systems now have features that were exclusive to the flexible PBX systems. These systems are referred to as ‘Hybrid’ systems.