You can change the outbound CallerID for any phone on your system. The CallerID must represent an existing number on any of your locations. Multi line appearance phones can use a different outbound CallerID for each line appearance or show "Blocked" which displays no CallerID. By default all phones and all line appearances are set to your primary DID / Number which is set in Addition Location Information under PHONE SYSTEM CONFIGURATION / Basic Settings for your location.
To make changes to your phone access the Star2Star web portal PHONE SYSTEM CONFIGURATION section see example below / left. Under Basic Settings click Extensions and select the extension you require. The Edit an Extension screen will display showing all Outgoing CallerID Line appearances for your phone. On the example shown below / right a 6 line appearance phone is being used. Note that the Line appearance 1 is set to system default, lines 2 and 3 are set to a specific DID / Number and line 6 is shown as blocked. By clicking the dropdown associated with each line appearance you can quickly select any DID / Number from any location on your system or use the system default (Primary DID) or show as "Blocked". When making changes remember to click Save Changes and Save Changes to System.