Cloud PBX explained: hosted PBX, SIP trunking and UCaaS
A PBX is the switchboard behind a business phone system. A cloud PBX moves that switchboard to the internet, so you get extensions, menus and call routing without a server in a cupboard. This guide explains the jargon in plain English.
PBX meaning
A private branch exchange (PBX) is the system that connects phones inside a business and links them to the outside phone network. It gives each person an extension, lets staff transfer calls and routes incoming calls to the right person or team.
For decades, a PBX was a box of hardware on site that needed specialist maintenance. Today most businesses use a cloud PBX instead.
What is a cloud PBX (hosted PBX)?
A cloud PBX, also called a hosted PBX or virtual PBX, is a PBX that your provider runs for you in secure data centres. Your phones and apps connect to it over the internet.
You control everything from a web dashboard:
- add or remove users and numbers
- record greetings and build call menus
- set business hours and holiday routing
- view call history and reports
Benefits of a cloud PBX
- No hardware to buy or maintain on site.
- Work from anywhere: extensions work on mobile and desktop apps.
- Fast changes: add a new starter in minutes.
- Built-in resilience: providers run services across several data centres.
- Predictable cost: usually a monthly fee per user.
On-premises PBX vs cloud PBX
| Factor | On-premises PBX | Cloud PBX |
|---|---|---|
| Upfront cost | Hardware and installation | Little or none |
| Maintenance | Your team or a contractor | The provider |
| Remote work | Extra setup needed | Built in |
| Scaling | Limited by the hardware | Add users online |
| Updates | Manual | Automatic |
What is SIP trunking?
SIP trunking connects a PBX you already own to the public phone network using the internet instead of traditional phone lines. Each "trunk" can carry many simultaneous calls. It suits businesses that have invested in an on-site PBX and want lower calling costs without replacing it. SIP trunking providers sell channels or usage-based plans; check current pricing with each provider.
If you do not already own a PBX, a cloud PBX is usually simpler than SIP trunking.
UCaaS meaning
UCaaS (unified communications as a service) combines business phone, video meetings, team chat and often file sharing in one cloud platform and one app. Most leading business VoIP providers now sell UCaaS plans. Compare them in our best VoIP for small business guide.
UCaaS vs CCaaS
- UCaaS helps employees talk to each other and to customers day to day.
- CCaaS (contact centre as a service) is built for teams that handle large volumes of customer calls and messages, with features such as skills-based routing, wallboards, workforce management and quality monitoring.
Many providers offer both and connect them.
Call routing features explained
Auto attendant
An auto attendant (or virtual receptionist) greets callers and offers a menu, such as "press 1 for sales, 2 for support". It can route by time of day, send callers to voicemail after hours and play announcements. It makes even a one-person business sound professional.
Ring groups
A ring group rings several phones at once or in order, so someone in the team picks up.
Call queues
A call queue holds callers in line with music or messages until an agent is free, and shows managers wait times.
Extensions and direct numbers
Each user gets a short internal extension for transfers, and can also have a direct number that customers dial.
How to move to a cloud PBX
- List your users, numbers and how calls should flow.
- Check your internet with the VoIP speed test.
- Choose a provider and start a trial.
- Build your auto attendant, ring groups and business hours.
- Port your numbers and train your team.
Frequently asked questions
What does PBX stand for?
PBX stands for private branch exchange, the internal phone switchboard that connects a business's phones and routes calls.
What is the difference between a cloud PBX and a hosted PBX?
They mean the same thing: a PBX that a provider runs in its data centres and you manage online.
What is SIP trunking used for?
SIP trunking connects an on-site PBX to the phone network over the internet. It lets businesses keep their existing PBX while lowering calling costs.
What does UCaaS mean?
UCaaS means unified communications as a service: phone, video meetings and chat delivered together from the cloud.
What is an auto attendant?
An auto attendant is an automated menu that answers calls and routes callers to the right person, team or voicemail.
Do I need IT staff to run a cloud PBX?
Usually not. Providers run the system, and you manage users and call flows in a simple web dashboard.
Keep reading
How we write: we explain the technology in plain English and compare providers on published features. We do not invent prices; plans change often, so check current pricing with each provider. Some links may earn us a commission at no cost to you (see our affiliate disclosure).