Business phone systems are the systems behind a company's main number. A business phone system rings the right person's desk, puts callers on hold, forwards calls to mobiles, records calls and, more and more often, writes down what was said. For decades, this was a box of hardware in an office cupboard, called a PBX. Since around 2010, the system has moved to the cloud and become a monthly subscription, called a cloud phone system, or UCaaS, short for unified communications as a service.
Many companies are somewhere in between. Their old PBX still works and still runs the desk phones. Replacing it means buying new equipment, training staff again, and risking failed calls during the change. So these companies move to the cloud in stages.
Here is a typical case. You call the main number of a property developer's office in Chandigarh to ask about a flat.
First, your call crosses your operator's network and reaches the company's phone line. Between the operator and the company, the call travels as data, using VoIP (voice over IP).
Second, the call enters the company. It passes through a session border controller (SBC), the device that connects the company's phone system safely to the operator's network. Then it reaches the old PBX in the office. The PBX plays the welcome message: "Press 1 for sales, press 2 for site visits." You press 1.
Third, a sales executive's laptop rings. She is working from home today. The company has already moved its sales team to a cloud phone system, so the PBX hands the call to it. The cloud system rings her softphone, a phone app on her laptop that carries her office extension. You hear the same office line, and you never see her mobile number.
Fourth, the call is written up. When you hang up, call transcription and AI summaries have already produced a transcript, a short summary and a task: "Send the floor plan of the three-bedroom flat in tower B by email today." The summary is saved in the sales team's records.
Fifth, the team meets. That afternoon, the executive discusses your enquiry with her manager on video conferencing and team chat, which comes in the same subscription as the phones.
A company with a large customer care team adds one more layer. Its support staff answer calls and chats in contact centre software, which runs on top of the phone system. And the calls themselves reach the company over operators' telecom networks.