Sangoma has it from small to large business !
https://www.sangoma.com/products/pbxact/
PBXact – Enhanced Business Phone Systems
The PBXact Business phone system is a fully-featured IP-PBX designed with unified communication features for organizations needing mobility, productivity and collaboration capabilities. The PBXact business phone system is available in both hardware and software versions. It comes with an extensive set of built-in Unified Communications features such as:
“Phone Apps”- Advanced productivity features controlled by the IP-Phone’s displayUCP web-based Dashboard allowing end-users to control phone settings, voicemail, conference rooms and more…Zulu UC Desktop and Soft-phone Integration for mobility and productivity.CRM Integration for screenpop and click to callEnd-Point-Manager to auto-provisioning Sangoma IP-Phones and manage each user’s programmable buttons and featuresBuilt-in VPN to guarantee security for your remote workers connecting to the corporate PBX
PBXact Hardware
PBXact hardware is purpose built to be a high-performance business phone system designed and rigorously tested for optimal performance. All Sangoma hardware carries a one year warranty with options to extend. Are you looking for PBXact Software?
PBXact 25
Supports up to 25 licensed extensions and 15 simultaneous calls.
PBXact 40
Supports up to 40 licensed extensions and 30 simultaneous calls.
PBXact 60
Supports up to 60 licensed extensions and 40 simultaneous calls.
PBXact 75
Supports up to 75 licensed extensions and 45 simultaneous calls.
PBXact 100
Supports up to 100 licensed extensions and 60 simultaneous calls.
PBXact 400
Supports up to 400 licensed extensions and 150 simultaneous calls.
PBXact 1200
Supports up to 1200 licensed extensions and 350 simultaneous calls.
PBXact 2000
Supports up to 2000 licensed extensions and 1500 simultaneous calls.
PBXact 5000
Supports up to 5000 licensed extensions and 1500 simultaneous calls.
PBXact Software
If you already have your own hardware or want to install PBXact on a virtual machine, you can install PBXact Software. It is the exact same software we use on our PBXact appliances and comes with a 50 user license. If you need more users we offer user bundles to provide you with the best value.
Install on your own hardware or VM
User and call support is only limited by on your hardware