You can choose whether to view information about a caller's identity before you answer the call. To use this service, you need a telephone that can display Caller ID information. Note that the caller's number is not displayed if the caller has withheld it. Call Waiting with Caller ID lets you see the caller's telephone number at the same time as hearing the Call Waiting tone. To use this service, you need a telephone that can display Call Waiting with Caller ID information.