Use one main line per extension

Hi
I have set up three main lines as trunks and an extension for each telephone number. How do I have to furnish you outbound routes now that each branch goes out over the correct main line? For example, I see that when I dial with the home number, the fax number or the business number is displayed on the phone called.
Where do I set that the correct number is displayed at the end, which is also used to call out?

Best regards
Diani