Cross tenant phone calling.
To allow phone calling from extensions belonging to tenant A, to extensions belonging to tenant B, you have to define conduits.
From menu Configuration choose More Configuration then choose Conduits.
Choose the tenant A, then create a conduit by specifying: a prefix, the tenant( for example B) we want to be able to call, define if you want the caller id to be altered(1) and if you want switch tenant(2).
(1) if you choose yes for this option the caller id will be modified adding the prefix (defined in tenant B for calling tenant A), so who is receiving the call can call back immediately, having the right number in his hands. Obviously this works if there is a mutual conduit defined in tenant B allowing calling to tenant A. Otherwise the caller id is the external number associated to the calling extension.
The "Switch Tenant" option is now always "YES"
(2) if you choose yes for this option the calling tenant will be altered and it seem the calling extension belongs to the called tenant also if the calling is forwarded to other numbers.