APPSC Group-I Preliminary Exam 2004 Solved Paper 1

The PTT (Push-To-Tallk) services, a mix of Internet Telephone and Wireless Wallkie-Tallkie, was announced by Tata Teleservices for its mobile telephone customers on May 27, 2004 - a unique technology which is available only in three other countries in the world. Identify the one which does not have this technology.