Understanding how PBX phone systems work is fundamental to understand modern phone systems in general. Private Branch Exchange systems are actually private telephone networks used within a company, administration, shop, or any other organization, in one or more sites, which needs to organize communications both internally and with the outside world. While they may seem complicated to install, these several families of phone systems offer many advantages.
Typical setup and main system types
A private brand exchange system involves many components, and can be arranged differently depending on the type of system.
How PBX systems work
PBX systems generally include telephone trunk lines, a computer with enough memory to manage calls and switching calls to the desired correspondent within the company and outside of it, a network of physical (PTSN) or virtual lines, and generally a central user console or switchboard.
Equipment needed includes cabinets, consoles, logic cards, computer, telecom trunks, telephone sets, uninterrupted power supply and... lots of wires.
In a typical setup, the system connects to IP phones through the internal lan, plus a gateway for fax machines, and the external network though the internet services provider and public switched telephone network (PSTN). These days, these systems are almost all IP PBX systems, meaning the connections are not made through the legacy phone system connections, but through Voice over IP connections.
Hosted systems, also called “Centrex” - for “central exchange” - or “virtual” systems, diverts the needs for businesses to invest in the necessary telephone equipment, as all the system is operated by the provider. This allows remote connections to the corporate network from PCs or mobile phones.
Advantages of PBX
These systems have many advantages, especially IPBX systems.
Advantages of these systems in general
The core advantages of these systems is that they allow companies or offices to have more phones and numbers than physical lines, and to have free calls between users. These systems will almost always support the following features: voice mail, auto ring back, auto dialling, auto directory services, ACD or automatic call distributor, call forwarding, call transfer, interactive voice menus (IVR), conference calls, speed dialling...
Also, technology used is almost always using open standards, so building a typical setup is very easy and affordable.
Advantages of IP PBX
These systems allow users to not rely on another line for telephony, as all call and computer data is channelled through the internet on IP protocol.
- This obviously allows businesses to use voice over IP (VoIP) technologies.
- Telephony services using the internet to channel calls are called Sip trunks, and allow users to have a great number of simultaneous calls on the same line, with cheap call rates.
- Mobile working is made possible as all that users need to connect to the company’s phone network is an internet connection, wherever they are in the world.