Here is how to set/change your caller ID.
Please note that you can only present the numbers that you actually have in your NUACOM account.
If you wish to use as a Caller ID a number that is not currently in NUACOM, you will need to port it over to NUACOM first.
The caller ID can be set per extension, to do that please log in to the NUACOM portal then go to Settings > Extensions and press on the extension you wish to edit.
From the "Caller ID" drop-down pick the desired number and press "OK".
Missing a number?
Please check the current user permissions in "Settings", "Users", locate the user, press "Edit".
Select the numbers allowed to be used by the user, save.