leejor said:
If that is what you want. When someone picks up a phone and dials an extension number, then all devices, that are assigned that number, and are registered
I think this is key. There are no "persons" in 3cx. There are just extensions. As an extension has a status, an email-address and a call history, it does make sense, to use the the extension as a person.
But sometimes an extension will be used for something else, like a room.
When we started, I wanted to provide every employee with it's own extension, even those, which were sharing a phone with colleagues. You can have several SIP-accounts on one phone, but it's difficult to manage, you will have to use the webinterface of the phone. I would advice to avoid this. In this case you could have an extension "office 2" or "Jack+Peter".
So extension are not the same as people in many scenarios. Often people want to sync their AD with the pbx. The AD is nice as a starting point, but in practice there are so many differences, that you don't want your AD to be synced to your pbx. The AD is for users, the pbx is for extensions.
I would love it, if sometime in the future there would be a "user" table/object inside the pbx. So you can assign multiple users to one extension (if they share a phone) and multiple extensions to one user (if the user is often moving between his office, the lab and ...). This would enable a lot of nice applications, including AD sync, a more sophisticated phonebook, which reflects the above secnarious and more. This way the call history for users could include multiple extensions ...