Caller ID shows you the numbers for most incoming calls, so you know who is calling before you answer. If you do not want to answer your Sprint PCS® phone, you can let the incoming call roll to your voicemail. Caller ID works whenever your phone is on. If the person calling you is someone you have entered into your phone's address book, the name of that entry will also be displayed. What's more, Caller ID safeguards your wireless calling privacy with Caller ID Block. When you initiate a call, you can decide whether your phone number is shown to the person you are calling.