Clearly sound - Please note that the volume of the headset and ringer are adjustable, the volume of the handset and speakerphone are not adjustable ^^ Caller ID allows you to properly route calls(Please note: it shows the phone number, not the name. ); 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 ^^ This landline telephone with headset is designed for call center affair, telemarketer, telephone counseling services, insurance, hospitals, banks, telecom operators; 3 methods of answering call: receiver, headset and hands-free key to let you customize your setup to maximize efficiency in your work area