A telephone system is a term which can be used for any network of multiple phones, although it’s generally used when it comes to the world of business – small or indeed larger offices, which have multiple departments and lines.
There are many providers when it comes to business telephone systems, for example, Siemens, NEC and Panasonic to name but a few. Each of these companies will offer different services, but all will include the basic elements you’d expect, such as hold music and voicemail. Most providers these days will also offer VoIP or Voice over IP (using the internet to chat over).
A larger enterprise might benefit from its own private branch exchange set up (PBX) – which is essentially a dedicated telephone exchange for the business in question. While a PBX isn’t cheap, you can find a reasonable enough price if you’re prepared to do a bit of comparing and contrasting of different offers.