What regular expression will match valid international phone numbers?
All country codes are defined by the ITU. The following regex is based on ITU-T E.164 and Annex to ITU Operational Bulletin No. 930 – 15.IV.2009. It contains all current country codes and codes reserved for future use. While it could be shortened a bit, I decided to include each code independently. This is for calls originating from the USA. For other countries, replace the international access code (the 011 at the beginning of the regex) with whatever is appropriate for that country’s dialing plan. Also, note that ITU E.164 defines the maximum length of a full international telephone number to 15 digits. This means a three digit country code results in up to 12 additional digits, and a 1 digit country code could contain up to 14 additional digits.