echo request/reply that is used to test whether a destination is reachable and responding. (Internet content provider) A service provider that specializes in providing content rather than infrastructure. ICT (information and communications technologies) A broad field concerned with technology and other aspects of managing and processing information. IDEA (International Data Encryption Algorithm) An algorithm developed Zurich that is free of charge for noncommercial use. Viewed as a good algorithm, it is used in PGP and in Speak Freely, a program that allows encrypted digitized voice to be sent over the Internet. IDF (intermediate distribution frame) A frame that has distributing blocks sides, permitting the interconnection of telephone circuitry. Glossary IDSL (ISDN DSL) IDSL (ISDN DSL) A transmission medium that has a maximum loop length of 3.4 miles (5.5 km) and is deployed as a single twisted-pair cable that offers 128Kbps in each direction. IDSL is not used much anymore. IEC (International Electrotechnical Commission) An international standards organiza- tion that deals with electrical, electronic, and related technologies. Some of its standards are developed jointly with the ISO. IEEE (Institute of Electrical and Electronics Engineers) A scientific, engineering, educational society that develops and publishes standards in a variety of electrical engineering and computer-related areas. IEEE membership is open to any dues-paying individual. The IEEE is responsible for 802 LAN standards. IETF (Internet Engineering Task Force) A nonprofit organization that produces the stan- dards used in TCP/IP and the Internet. I-frame (intracoded frame) A frame that is not reconstructed from another frame. An I-frame is also a reference frame; it serves as a reference to construct other frames. IFRB (International Frequency Registration Board) A board within the ITU that is responsible for the maintenance of an international list of radio frequency usage and the alloca- tion of new frequencies. IGMP (Internet Group Management