No single country uses the telephone code 0035. When an additional digit is added, the numbers 00350 through 00359 are divided between 10 European countries. The digit combination of 00 is the exit code used by many countries, including Britain. The exit code for the United States is 011.
In the first book of European international dialing codes compiled in the 1960s, known as "the red book," Hungary had the dialing code 35. The regulation of international dialing codes is the responsibility of the International Telecommunications Union, which is part of the United Nations. It also specializes in all types of information and communication technology.