There is no single country that uses the two-digit code 35. A further digit needs to be added to attain a correct international dialing code. When a further digit is added, the numbers 350-359 are divided between ten European countries.
In the CCITT Red Book, a list of European International Dialing codes compiled around in the 1960s, Hungary had the dialing code 35. The red book has since been updated. Regulation of the international dialing codes is the responsibility of the International Telecommunications Union. It is part of the United Nations and specializes in all types of information and communication technology.