Application of the United States of America in the Matter of an Order Authorizing the Use of a Pen Register or Similar Mechanical Device

MEDINA, Circuit Judge:

This important and interesting case involves the Government’s application for an order authorizing the installation and use of a pen register, and directing the New York Telephone Company to provide information, facilities and technical assistance to Special Agents of the Federal Bureau of Investigation in the installation and- operation of the device. A pen register is a mechanical instrument attached to a telephone line, usually at a central telephone office, which records the outgoing numbers dialed on a particular telephone. In the case of a rotary dial phone, the…