See who is calling you from your phone’s display. When you receive a call, their phone number will appear on your telephone’s display window. If someone else calls while you are on the phone, you can see that number also, giving you the opportunity to take that call or let it go to voice-mail. You can customize your outgoing caller ID, so you are in control of what shows up when you call other people. Each extension can be set to display your main phone number, or other phone numbers you have.