r system of country codes for European use was mentioned in the 1960 CCITT Red Book. Some of these country codes were retained in the CCITT country code assignments and remain in effect (for example, France +33, United Kingdom +44).For further details on country code history and development, see History of Country Codes (WTNG).See also[සංස්කරණය]E.164International Telecommunication UnionList of international call prefixesInternational mobile phone codesTelephone numbering planGroup identifiers in ISBNs, a similar form of country codeLocal conventions for writing telephone numbersReferences[සංස්කරණය]↑ not yet implemented↑ 2.0 2.1 2.2 2.3 Sint Maarten will join the North American Numbering Plan on 30 September 2011, at which time it will adopt dialing code +1 721.[4]↑ "European Telephony Numbering Space (ETNS)". 28 මැයි 2009. සම්ප්‍රවේශය 20 ඔක්තෝබර් 2010.↑ "PL-423: Updated Information -  Introduction of NPA 721 (Sint Maarten)" (PDF). North American Numbering Plan Admin