Traditional phone systems (PBX or On-Premise systems) have been around for over 100 years now. They are still a viable solution for many companies, but are typically more expensive over time.

Upfront costs:

PBX -A traditional major brand phone system can average between $500-$1500 a phone depending on the features needed. This price would include the phones, the PBX (the brains), and programming/customization.
Cloud -typically the only cost are the phones at $100-$200 a piece depending on model.

Ongoing Maintenance costs:

PBX -As the manufacturer upgrades, features and patches bugs, and increases security, you will need to have your system patched as well. This would be part of a monthly maintenance subscription or paid on Time & Material, but is not often discussed in the sales process.
Cloud -None. Simple as that. It’s included and done automatically.

Expansion:

PBX -Requires licensing (one time or annual), hardware and onsite installation services.
Cloud -Call and order a new extension, it is delivered pre-programmed and ready for use.

Downsizing:

PBX -You bought it, you own it.
Cloud -Call in and have an extension turned off (temporarily or permanent) the next billing cycle will reflect the reduced services.

Multiple or home office locations:

PBX – Requires licensing (one time or annual), hardware, onsite installation services, and often upgrades in the network to support VPN.
Cloud – Call and order a new extension(s), it is delivered pre-programmed and ready for use anywhere in the world.