Abstract: A resettable timer conformed as an interface assembly between a nurse call button and the wall jack therefor, including a D.C. power supply driving a timing circuit which closes a switch in parallel with the call button at the completion of a predetermined interval of time. The arrangement of this timing circuit into an interface stage received in the jack at the patients bedside requires that the nurse visit the patient in order to effect a reset. Thus the nurses call signal will remain on in an indistinguishable manner from an emergency signal, calling for response which can only be corrected by a visit to the patient's room.