ADTRAN, Inc. is an established provider of advanced transmission products for today's expansive telecommunications networks. ADTRAN products support most major technologies, including internetworking, access routing, fiber, T3, T1, E1, wireless T1/E1, ATM, Frame Relay, SHDSL, VPN, SDSL, HDSL, HDSL2, ISDN, and DDS. According to Gartner/Dataquest and IDC, ADTRAN has gained the leading market position in enterprise integrated access devices and HDSL, while maintaining its leadership position for the fourth year in a row in T1 and subrate CSU/DSUs, Frame Relay/DDS extension, and ISDN extension. ADTRAN equipment serves the major Incumbent Local Exchange Carriers, interexchange carriers, ISPs, Competitive Local Exchange Carriers, international service providers, public and private enterprises, and original equipment manufacturers.