When a user has on more DIDs assigned a Caller ID selection tab is shown on the client
The Caller ID selection tab is used by the user to select a Caller ID which will be used for his outbound calls.
Caller ID selection screen with 3 numbers
Selecting a DID
From the Caller ID selection tab.
Click on the number you want to select
When you click a number the server is notified to change the Caller ID in the PBX configuration. If the change is successful, the phone icon will become a solid color.