An optional service using the Caller IDThe caller ID gives the subscriber the ANI of the incoming call. An optional service that transmits the telephone number of the originating caller to a receiving telephone device.  Some Caller ID may also provide directory name listing information services. system. This system has the capability of displaying the phone number of the caller who is calling in while the line is in use via call waitingCall waiting is a feature that will notify you that another person is attempting to call. The caller does not receive a busy signal. To deactivate Call Waiting with some LECs, dial *70..