The country dialing code for Argentina is 0054 for calls being made out from a country with an exit code of 00. For calls made to Argentina from a country with a different exit code, a caller would dial his country's exit code followed by 54.
Placing an international call requires an exit code and a country code in addition to the phone number being dialed. Exit codes are used for dialing out of a country. For most countries, the exit code is 00 or 011. The exit code is then followed by the unique country code of the country being called.