What it actually means
PBX stands for Private Branch Exchange, the bit of kit that sits between the outside world and your internal phones and decides where a call goes. The traditional version was a physical box in a cupboard, expensive to buy, painful to move, and only as clever as the engineer who last touched it. A hosted PBX moves all of that logic into the cloud. Your phones, whether they're desk handsets, mobile apps or softphones running on a laptop, register with a platform over the internet and the routing rules live there.
In practical terms you get call flows you can edit yourself (press 1 for sales, press 2 for accounts), voicemail to email, call recording for training and compliance, hunt groups so a call rings the whole team or a rota, integration with CRMs like HubSpot and Salesforce so the customer record pops on screen when the phone rings, and a Microsoft Teams plug in so colleagues can dial out from inside Teams. Licensing is per user per month, and you can add or remove seats in minutes.
In business
What this looks like at work
The felt cost of getting this wrong is money walking out of the building. The inbound sales call at 8:55am that nobody picked up because the auto attendant routed it to a desk phone in an empty office. The existing customer transferred three times because the receptionist couldn't see who was free, who eventually gave up and rang a competitor. The evening enquiry that hit a dead line because the system has no concept of out of hours, no overflow to a mobile, no voicemail that actually gets read. For a six person sales team a single missed buyer a week is real revenue, and for a service business every unanswered call is a job booked elsewhere.