I have been searching around to find a reliable answer on how many extensions a freepbx machine can handle (imagine no limitation comes from hardware). it seems Sangoma suggests maximum 2000 users on one server regardless on how powerful is the server.
Would be great if someone can shed some light on this.
Server capacity is primarily limited by number of concurrent calls and number of calls per second.
A large server would do fine in a 3000 room hotel, because very few guests use the room phone anymore; you’d rarely have more than 20 calls in progress.
In a business where the users routinely make and receive calls, even 1000 extensions is a stretch, especially if calls are being transcoded and/or recorded.
Server sizing is mostly just a bunch of voodoo and guessing by people who look like they know whats going on. In all reality you can have two identical machines and one will do fine with 500 extensions and the other will struggle. It comes down to what you are doing. Are you trans-coding, call recording, playing music, doing some other heavy task per extension. There are a ton of factors that are outside of pure user count. I personally wouldn’t go over 300-500 on any single server. I don’t even like a single point of failure for that many people.
Back in 2019(ish) we were optimizing FreePBX to handle 5000 users. This was mostly around handling load times and configurations and not actual simultaneous use of 5000 users. I would just ask hey if this server goes down for any reason, how many people do I want sitting around without phones. Whatever that number is, divide your user base by that and add servers until you have what you need.