Pack size 1 phone the bt4000 big button has large buttons making it not only practical for elderly customers but also an aid to sight hearing and dexterity impaired customers fed up with sales calls interrupting you at home the new bt4000 big button brings you unique functionality to block nuisance or unwanted calls its call management feature puts you back in control by enabling you to choose the calls you want to take and those you want to block designed in the uk the bt