If a user is not in a Caller ID Presentation profile the caller ID presented is not the Default caller ID number but it is the Contact telephone that shows up as the caller ID. If the Contact telephone is not entered then a generic voice-ring telephone number shows up as the caller ID.
Also, if the user is in a Caller ID presentation profile that has use DID checked but does not have a telephone number entered, if the user does not have a DID then the Default caller ID number field should be used.
On the organization page, the Default caller ID number should be used for users not in a caller ID presentation profile