Cloud, SIP, PRI or analog
Four ways to carry business calls, and the handful of facts that separate them.
What is the difference between them?
They are four ways to carry calls. Cloud means the phone system and the lines both come as a service. SIP trunks are digital lines feeding a system you own. A PRI is an older digital circuit with a fixed 23 channels. Analog is one copper line per call.
| What it is | Needs on site | Best for | |
|---|---|---|---|
| Cloud | Phone system and lines delivered over the internet | Internet, handsets or apps | Most offices, remote staff, anyone who does not want hardware |
| SIP trunks | Digital lines feeding a phone system you own | Your own system, plus a connection | Keeping working equipment while dropping old line costs |
| PRI | A dedicated circuit carrying 23 voice channels | Your own system and the circuit | Sites already on one, with heavy simultaneous call volume |
| Analog | One copper line per conversation | A line per device | Lifts, fire panels and other standalone equipment |
How to read the table
- Cloud and SIP both ride on your internet connection — the difference is who owns the phone system
- A PRI is sized in fixed blocks of 23 channels, so a 24th simultaneous call needs a second circuit
- SIP channels are usually added or removed one at a time, which is why most PRI sites move to them eventually
- Analog is the only one that works without a network, which is exactly why life-safety equipment still uses it
- You can mix them. Cloud for the desks and analog for the lift is a completely normal setup
Which one to pick
Start with the system, not the lines
Whether you want a hosted system or your own equipment decides most of this. That question is covered in which phone system.
If you want hosted, you want cloud
The lines come with it. There is nothing else to choose.
If your on-site system works, look at SIP
It usually keeps the equipment and the numbers while replacing what the lines cost each month.
If you are on a PRI, count your simultaneous calls
Most sites use a fraction of 23 channels and are paying for the rest.
Keep analog only where a device demands it
The audit in analog lines is the fastest version of this.
What the monthly cost is made of
Cloud is priced per user, so headcount drives it. SIP is priced per channel, so simultaneous calls drive it. A PRI is priced as a whole circuit whether you use it or not. Analog is priced per line. Setup fees and handsets sit on top of all four, and vary by provider.
What should you check first?
Look at what happens when the building loses internet. Cloud and SIP calls stop arriving unless calls are set to fall back to mobiles, and that fallback has to be configured before you need it. Whatever you choose, the service agreement you sign with your provider is what binds you.
Last reviewed September 14, 2026
