The code "01" is not an international country code by itself. Instead:

• The country code "1" is assigned to the United States, Canada, and several Caribbean nations under the North American Numbering Plan (NANP). This code is followed by a three-digit area code specific to each region within these countries

• In the United States and Canada, area codes do not start with 0 or 1. The initial digit of an area code cannot be 0 or 1, so "01" is not a valid area code in these countries

• The prefix "01" is sometimes seen in UK phone numbers as the start of geographic area codes, but "01" alone is not a complete area code. UK area codes that begin with "01" represent specific cities or towns (e.g., 0114 for Sheffield, 0131 for Edinburgh)

• The "01" prefix can also appear as part of national dialing codes in other countries, but it is not a standalone country code

In summary, "01" is not a country code or a valid area code by itself. The country code "1" is for the US, Canada, and related countries, and area codes in those countries never start with 0 or 1. In the UK, "01" starts area codes for geographic regions but is not an area code on its own. If you have a phone number starting with "01," it is likely a UK geographic area code prefix, not a country code. If you mean "01" as a country calling code, no country uses "01" alone as a country code. The US and Canada use "+1" as the country code