VoIP Telephone Systems

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What is VoIP?

From one angle, the normal user doesn't really need to know how his phone system works; he just wants to make and receive calls, and maybe use a few other functions. For him it is unimportant whether he's using VoIP or not, all phone systems should carry out at least those basic tasks.

A VoIP telephone system will do everything an ordinary system will do, and on a basic level, in exactly the same way. The phones look like normal phones. If it rings, you can pick it up and speak. Or you can dial a number, just like you always have.

But like most technological advances, it's the new features and capabilities that are worth knowing about, so that you can take advantage of those that benefit your business.

To more easily understand the differences, let's have an overview of how they work.

In a standard system, it is based around a central unit, called a PBX. All extensions are connected via phone cables to this central unit. The PBX has a number of connections for extensions which can sometimes be increased as the company grows, but which has a fixed limit beyond which it can be expanded no further. This is due to the physical limitations of the PBX box itself.

All calls must come and go via BT telephone lines. Similar to the extension connections, the lines to the BT network have a maximum limit for phone line connections. This determines the maximum number of calls that can be made at any time. It is often the reaching of these limits that force companies to change or upgrade systems.

Another limitation to incoming call lines may come externally from BT. In some locations, particularly rural, there may be no further lines available, or only possible with payment of a prohibitive installation charge.

On the system itself, there is often a reception console with more features and indicators which show extensions busy etc.

Like the old system, this system is also based on a central PBX, this time a VoIP unit.

The first difference to be noticed is that the telephones and computers can share the same network cabling - the phones don't need a separate set of cables. However, unless you're using cordless phones, they do still need to be connected with wires and so make sure that there are enough sockets to cope.

VoIP stands for "Voice over Internet Protocol". It may sound geekish, but it basically means that the phones and computers communicate using the same 'language', whether inside the office building or externally over the internet. Hence they can share the same computer network system as the PCs, printers, server and anything else.

In the diagram above, there are some extension phones and also a USB phone which is connected directly to a PC. All can make or receive calls and any other functions of the system, but the latter can interact directly with the users PC for additional ease of use and functionality.

Another major difference is in the external connectivity. Where the legacy system connects to the outside world only through BT phone lines, a VoIP system can use both BT and the internet to make and receive calls. The latter firstly gives additional redundancy, but secondly adds the ability to make cheap or even free calls (especially overseas calls) and to link to other offices and remote/home workers.

If there are restrictions on the amount of lines that BT can supply, this can be overcome with additional capacity being achieved via the internet connection.