The analogue telephone was invented by Alexander Graham Bell in 1876. Telephones communicated through various exchanges or switchboards which were manually operated. The exchanges served specific geographic areas.
The technology did not advance much in the next 100 years except the adoption rate. I remember calling neighbouring farms using a party line on my grandfather’s farm in the late 1970’s with a Pendulum Telephone.
Automation of the switchboards led to the introduction of the Public switched telephone network (PSTN). Telkom still operate South Africa’s only fixed line PSTN. This allowed tone dialling instruments to communicate globally by dialling a number.
This led to the introduction of Private Automated Branch Exchange (PABX) or Private Branch Exchange (PBX). It is a business telephone system that performs call processing duties in an office with multiple telephone lines (trunks) and multiple handset telephones (extensions). The call processing duties of the PABX include: Establishing, maintaining and disconnecting a connection between two telephones, and providing call accounting information about the call.
PABX systems offer the following features of which some are optional extras:
- Auto attendant or welcome message to greet and direct callers automatically
- Automated directory where callers can be routed to a specific extension by typing or speaking the letters of the user’s name
- Automatic call distribution (ACD) where the system automatically routes calls based on criteria like number dialled, caller id, time of day or route selection
- Automatic call back
- Call forwarding on busy or unavailable
- Call pick-up
- Call transfer
- Call waiting
- Conference calling
- Direct inward dialling (DID) to an extension
- Do not disturb (DND)
- Find me follow me: Allows a user to have multiple phones connected to the PABX and the system will find the extension you are available on or present your voicemail to the caller
- Music on hold
- Night service
- Paging via an external paging system or the speaker phones
The PABX evolved in the 1980’s with the introduction of digital telephones and Digital Enhanced Cordless Telecommunications (DECT) cordless telephones. Digital phones offer better security between the phone and the PABX and more information is passed between the phone and the PABX e.g. Caller Line Identity, feature codes and extension availability.
The 1990’s saw the introduction of IP Telephony. IP Telephony is voice communication over a data network. The traditional PABX manufacturers added IP Telephony functionality to their existing Analog/Digital PABX systems (called Hybrid PABX’s) and some pioneering manufacturers produced pure IP Telephony systems. IP Telephony introduced us to the soft phone whereby a PC with a headset can be used as a phone. Some IP Telephony systems are hardware based with all the call processing happens on a physical appliance and others are software based whereby the software can run on a file server or a Virtual Machine (VM). Asterisk PBX is a Linux open source software-based PBX created in 1999. The Asterisk software is embedded in many commercial, free and proprietary IP PBX systems. It supports open standards for voice communication e.g. Session Initiation Protocol (SIP) which allows any standards-based SIP device to use the PBX. This means your organization is not locked into using a particular brand of IP handset and drives the cost of IP handsets down.
The advent of IP Telephony, the increasing throughput of the internet and the declining cost of the internet paved the way for Voice over IP (VoIP). VoIP is simply voice calls made over the internet. VoIP calls can be made between offices at only the cost of the bandwidth and using a VoIP provider calls can be made to any geographic or non-geographic number. VoIP providers in South Africa like uVoice charge between 30% and 60% less than Public switched telephone network (PSTN) providers for calls and calls between your sites on VoIP are free of call charges.
IP Telephony and VoIP also enabled Unified Communications (UC). UC is the integration of communication services such as instant messaging (IM or chat), presence information, extension mobility, voice, audio, web & video conferencing, data and desktop sharing. The components of UC may include a combination Web conferencing services, on-premises video conferencing systems, collaboration tools like Microsoft Office 365, IP Telephony systems and Hosted PBX systems.
With the global trend for organizations to focus on their core businesses instead of expending resources on computer infrastructure and maintenance, organizations are opting for cloud computing services. VoIP, stable and quick internet connections make it possible to provide cloud PBX services to your organization. These services are referred to Hosted PBX, Cloud PBX or Virtual PBX services. This is a move away from a Capex based on-premises PBX service to an Opex based off-site PBX service. Organizations able to port their telephone numbers to the Hosted PBX provider and keep the number indefinitely. This enables the cancelling of expensive traditional Telco lines and presents the opportunity to pay between 30% to 60% less for calls.
Looking to the future there is a place for traditional/Hybrid PABX’s, IP Telephony and Hosted PBX services dependant on where the office is situated nearest to a support centre, the stability of the telephone lines, the availability of a high-speed internet connection and the features that are required i.e. just dial-tone vs call centre functionality.