A feature allowing individuals to dial in and use a firm’s telephone system from a remote location (thus making it a ripe target for phreaking exploits) and place telephone calls for free. Though, in theory, access to the DISA port is protected by a pass code, these pass codes are not difficult for crackers to ascertain. According to security experts, any business having a telephone system that allows employees to access it when away from their offices is vulnerable to phreakers. Access to such telephone systems can be made through the DISA, voice mail, and remote maintenance ports, even when they are not activated.
Lee, M-Y. Prevent Toll Fraud on Your Telephone Lines. [Online, January 14, 2002.] Entrepreneur.com Inc., Website. http://www.entrepreneur.com/article/ 0,4621,296289,00.html.