Morgan Edward O'Brien (1944- ), chairman of Cyren Call Communications,[1] is a pioneer in U.S. wireless telecommunications. As the co-founder and chairman of Nextel Communications, Inc. (now part of Sprint Nextel Corp.), O'Brien led the creation of the first all-digital nationwide wireless network (the Nextel National Network using iDEN technology developed by Motorola for Nextel) and brought push-to-talk (PTT) communication to the mass business and consumer market. He is considered by many to be a visionary leader who has shaped the wireless industry throughout his career.[2]