What is a tenant?
It might be simpler to answer by the opposite: what is not a tenant?
A tenant is not a user, nor an extension or any other button type. Any FOP2 license will show unlimited buttons and will allow to have unlimited users.
FreePBX is not a multi tenant system, so it is not affected by this limit. If you use FreePBX, then do not worry about possible limits as you won't find them.
There are other backends that are multi tenant by nature, like MiRTA PBX. Those systems let you create several PBXs on the same server. They let you partition the server configuration in separate and isolated compartments or contexts, and those partitions might have the same extension numbers but without being related with each other. These systems are used by VOiP hosting providers.
FOP2 can be installed on such servers, and can be used to display separate panels for each tenant, in the same fashion you can configure Asterisk for them.
The standard FOP2 license will show up to five tenants on a single server. In order to show more, you must extend the license. Please remember that this limitation applies only to multi tenant Asterisk installations. If you use FreePBX or derivatives like Elastix 2.x or Elastix 4, PBX in a Flash, etc, you won't need any license extensions to have unlimited users and buttons working.
A tenant is not a user, nor an extension or any other button type. Any FOP2 license will show unlimited buttons and will allow to have unlimited users.
FreePBX is not a multi tenant system, so it is not affected by this limit. If you use FreePBX, then do not worry about possible limits as you won't find them.
There are other backends that are multi tenant by nature, like MiRTA PBX. Those systems let you create several PBXs on the same server. They let you partition the server configuration in separate and isolated compartments or contexts, and those partitions might have the same extension numbers but without being related with each other. These systems are used by VOiP hosting providers.
FOP2 can be installed on such servers, and can be used to display separate panels for each tenant, in the same fashion you can configure Asterisk for them.
The standard FOP2 license will show up to five tenants on a single server. In order to show more, you must extend the license. Please remember that this limitation applies only to multi tenant Asterisk installations. If you use FreePBX or derivatives like Elastix 2.x or Elastix 4, PBX in a Flash, etc, you won't need any license extensions to have unlimited users and buttons working.