Clearly sound - The phone has a volume control button to allow for increasing or decreasing headset sound; Ringing sound High and Low selection. please make sure that the handset indicator light is on, that means the phone is on handset answering status. If the phone is not on handset answering status, please press the headset button to close headset answering method. Then the handset indicator light will be on when you answering the calls Caller ID and call waiting capabilities further support call management, allowing you to properly route calls; 5 levels of large display contrast adjustable allows for easy viewing the number, time and date; Audio output interface to record business calls for training or any other purpose 62 groups of incoming calls memory and 16 groups of outgoing calls memory; 5 groups 1-touch speed dial memories and 10 groups 2-touch speed dial memories; 5 area code to filter-no more nuisance calls; Mute function to silence the caller when you need to talk with others