Should you own your phone system's PBX or let a cloud provider run it?
Summary
That is the real decision hiding behind the PBX, VoIP, and cloud labels, since VoIP is only the way voice travels and both setups use it. Owning the PBX means paying for software or hardware up front and handling maintenance and outside lines yourself. A cloud phone system moves the PBX to the provider's data center, and you pay per user every month for as long as you use it.
Engine or gasoline
A PBX routes calls between your extensions and outside lines. VoIP carries the voice over an IP network. A cloud phone system is a PBX sold as a service. Asking "PBX or VoIP?" is like asking "engine or gasoline?" If you connect your own PBX to a SIP trunk, an outside line delivered over the internet, you still own the PBX but your calls ride on VoIP. 3CX puts it this way: the IP PBX is the phone system, and SIP trunking is the service that connects it to external networks.
How the bills differ
Cloud phone plans are normally priced per user. Owned systems often are not. 3CX licenses by simultaneous calls, not by the number of users: a company with 26 to 50 users falls in the 16-simultaneous-call tier, and 3CX describes its pricing as per system, not per seat. A business with many staff but few people on the phone at the same moment gets more out of that model than one where everyone is on calls at once.
Outside lines are a separate purchase when you own the PBX. AWS lists the pieces of a typical SIP trunk bill as a setup fee, a monthly charge for the broadband line, a price per channel that may include a call allowance, and the call charges themselves. Trunks are usually sold per channel, based on the most calls you expect to run at once.
Owning doesn't have to mean a box in the closet
The same 3CX software can run on your own Windows or Linux server, including virtual machines on VMware, KVM, or Hyper-V; in your own account on Google, Amazon, Azure, DigitalOcean, and others; or hosted by 3CX. The hosted option looks a lot like a cloud phone service from the outside, but the licensing still follows simultaneous calls.
Keeping an old PBX a little longer
If your PBX still works, you can switch only its outside lines to SIP trunks. 3CX notes that a VoIP gateway can let an older PBX talk to SIP trunks. The push can come from the carrier side as well: 3CX says lines like ISDN BRI, E1, and T1 are being phased out, that many European countries have already shut ISDN down, and that the UK is aiming for a full switch-off by 2027.
Sources
Related on this site
- What is VoIP, and how is it different from a regular phone line?
- Is a cloud PBX any different from hosted VoIP or a cloud phone system?
- Is SIP just another word for VoIP?
- What do you give up when you swap a landline for a cloud phone system?
- Is 3CX actually cheaper than paying for a phone service per user?
- What happens to Avaya Cloud Office customers now that the service redirects to RingCentral?
- Do business phone providers charge by the user, the line, or the company?
Written by Kaz (pen name). Figures are copied from providers' published pricing pages on the dates shown. We have not used these products. Corrections: contact form.