En la próxima versión de Backend Frontend Template: the WordPress Plugin Template se va a incluir una función que devolverá un array con los códigos en letra de cada país, su nombre y su código numérico que sirve como prefijo teléfonico (+34 para España).

Sin embargo no todo es WordPress, un programador de PHP puede aprovechar este trabajo, así que lo dejo aquí este código para que internet pueda aprovechar este conocimiento:

$countries_codes_names_and_numbers = [
	'AF' => [
		'name'   => 'Afghanistan'
		'code' => '93',
	],
	'AX' => [
		'name'   => 'Aland Islands'
		'code' => '358',
	],
	'AL' => [
		'name'   => 'Albania'
		'code' => '355',
	],
	'DZ' => [
		'name'   => 'Algeria'
		'code' => '213',
	],
	'AS' => [
		'name'   => 'American Samoa'
		'code' => '1684',
	],
	'AD' => [
		'name'   => 'Andorra'
		'code' => '376',
	],
	'AO' => [
		'name'   => 'Angola'
		'code' => '244',
	],
	'AI' => [
		'name'   => 'Anguilla'
		'code' => '1264',
	],
	'AQ' => [
		'name'   => 'Antarctica'
		'code' => '672',
	],
	'AG' => [
		'name'   => 'Antigua And Barbuda'
		'code' => '1268',
	],
	'AR' => [
		'name'   => 'Argentina'
		'code' => '54',
	],
	'AM' => [
		'name'   => 'Armenia'
		'code' => '374',
	],
	'AW' => [
		'name'   => 'Aruba'
		'code' => '297',
	],
	'AU' => [
		'name'   => 'Australia'
		'code' => '61',
	],
	'AT' => [
		'name'   => 'Austria'
		'code' => '43',
	],
	'AZ' => [
		'name'   => 'Azerbaijan'
		'code' => '994',
	],
	'BS' => [
		'name'   => 'Bahamas'
		'code' => '1242',
	],
	'BH' => [
		'name'   => 'Bahrain'
		'code' => '973',
	],
	'BD' => [
		'name'   => 'Bangladesh'
		'code' => '880',
	],
	'BB' => [
		'name'   => 'Barbados'
		'code' => '1246',
	],
	'BY' => [
		'name'   => 'Belarus'
		'code' => '375',
	],
	'BE' => [
		'name'   => 'Belgium'
		'code' => '32',
	],
	'BZ' => [
		'name'   => 'Belize'
		'code' => '501',
	],
	'BJ' => [
		'name'   => 'Benin'
		'code' => '229',
	],
	'BM' => [
		'name'   => 'Bermuda'
		'code' => '1441',
	],
	'BT' => [
		'name'   => 'Bhutan'
		'code' => '975',
	],
	'BO' => [
		'name'   => 'Bolivia'
		'code' => '591',
	],
	'BA' => [
		'name'   => 'Bosnia And Herzegovina'
		'code' => '387',
	],
	'BW' => [
		'name'   => 'Botswana'
		'code' => '267',
	],
	'BV' => [
		'name'   => 'Bouvet Island'
		'code' => '47',
	],
	'BR' => [
		'name'   => 'Brazil'
		'code' => '55',
	],
	'IO' => [
		'name'   => 'British Indian Ocean Territory'
		'code' => '246',
	],
	'BN' => [
		'name'   => 'Brunei Darussalam'
		'code' => '673',
	],
	'BG' => [
		'name'   => 'Bulgaria'
		'code' => '359',
	],
	'BF' => [
		'name'   => 'Burkina Faso'
		'code' => '226',
	],
	'BI' => [
		'name'   => 'Burundi'
		'code' => '257',
	],
	'KH' => [
		'name'   => 'Cambodia'
		'code' => '855',
	],
	'CM' => [
		'name'   => 'Cameroon'
		'code' => '237',
	],
	'CA' => [
		'name'   => 'Canada'
		'code' => '1',
	],
	'CV' => [
		'name'   => 'Cape Verde'
		'code' => '238',
	],
	'KY' => [
		'name'   => 'Cayman Islands'
		'code' => '1345',
	],
	'CF' => [
		'name'   => 'Central African Republic'
		'code' => '236',
	],
	'TD' => [
		'name'   => 'Chad'
		'code' => '235',
	],
	'CL' => [
		'name'   => 'Chile'
		'code' => '56',
	],
	'CN' => [
		'name'   => 'China'
		'code' => '86',
	],
	'CX' => [
		'name'   => 'Christmas Island'
		'code' => '61',
	],
	'CC' => [
		'name'   => 'Cocos (Keeling) Islands'
		'code' => '61',
	],
	'CO' => [
		'name'   => 'Colombia'
		'code' => '57',
	],
	'KM' => [
		'name'   => 'Comoros'
		'code' => '269',
	],
	'CG' => [
		'name'   => 'Congo'
		'code' => '242',
	],
	'CD' => [
		'name'   => 'Congo, Democratic Republic'
		'code' => '243',
	],
	'CK' => [
		'name'   => 'Cook Islands'
		'code' => '682',
	],
	'CR' => [
		'name'   => 'Costa Rica'
		'code' => '506',
	],
	'CI' => [
		'name'   => 'Cote D\'Ivoire'
		'code' => '225',
	],
	'HR' => [
		'name'   => 'Croatia'
		'code' => '385',
	],
	'CU' => [
		'name'   => 'Cuba'
		'code' => '53',
	],
	'CY' => [
		'name'   => 'Cyprus'
		'code' => '357',
	],
	'CZ' => [
		'name'   => 'Czech Republic'
		'code' => '420',
	],
	'DK' => [
		'name'   => 'Denmark'
		'code' => '45',
	],
	'DJ' => [
		'name'   => 'Djibouti'
		'code' => '253',
	],
	'DM' => [
		'name'   => 'Dominica'
		'code' => '1767',
	],
	'DO' => [
		'name'   => 'Dominican Republic'
		'code' => '1809',
	],
	'EC' => [
		'name'   => 'Ecuador'
		'code' => '593',
	],
	'EG' => [
		'name'   => 'Egypt'
		'code' => '20',
	],
	'SV' => [
		'name'   => 'El Salvador'
		'code' => '503',
	],
	'GQ' => [
		'name'   => 'Equatorial Guinea'
		'code' => '240',
	],
	'ER' => [
		'name'   => 'Eritrea'
		'code' => '291',
	],
	'EE' => [
		'name'   => 'Estonia'
		'code' => '372',
	],
	'ET' => [
		'name'   => 'Ethiopia'
		'code' => '251',
	],
	'FK' => [
		'name'   => 'Falkland Islands (Malvinas)'
		'code' => '500',
	],
	'FO' => [
		'name'   => 'Faroe Islands'
		'code' => '298',
	],
	'FJ' => [
		'name'   => 'Fiji'
		'code' => '679',
	],
	'FI' => [
		'name'   => 'Finland'
		'code' => '358',
	],
	'FR' => [
		'name'   => 'France'
		'code' => '33',
	],
	'GF' => [
		'name'   => 'French Guiana'
		'code' => '594',
	],
	'PF' => [
		'name'   => 'French Polynesia'
		'code' => '689',
	],
	'TF' => [
		'name'   => 'French Southern Territories'
		'code' => '262',
	],
	'GA' => [
		'name'   => 'Gabon'
		'code' => '241',
	],
	'GM' => [
		'name'   => 'Gambia'
		'code' => '220',
	],
	'GE' => [
		'name'   => 'Georgia'
		'code' => '995',
	],
	'DE' => [
		'name'   => 'Germany'
		'code' => '49',
	],
	'GH' => [
		'name'   => 'Ghana'
		'code' => '233',
	],
	'GI' => [
		'name'   => 'Gibraltar'
		'code' => '350',
	],
	'GR' => [
		'name'   => 'Greece'
		'code' => '30',
	],
	'GL' => [
		'name'   => 'Greenland'
		'code' => '299',
	],
	'GD' => [
		'name'   => 'Grenada'
		'code' => '1473',
	],
	'GP' => [
		'name'   => 'Guadeloupe'
		'code' => '590',
	],
	'GU' => [
		'name'   => 'Guam'
		'code' => '1671',
	],
	'GT' => [
		'name'   => 'Guatemala'
		'code' => '502',
	],
	'GG' => [
		'name'   => 'Guernsey'
		'code' => '44-1481',
	],
	'GN' => [
		'name'   => 'Guinea'
		'code' => '224',
	],
	'GW' => [
		'name'   => 'Guinea-Bissau'
		'code' => '245',
	],
	'GY' => [
		'name'   => 'Guyana'
		'code' => '592',
	],
	'HT' => [
		'name'   => 'Haiti'
		'code' => '509',
	],
	'HM' => [
		'name'   => 'Heard Island & Mcdonald Islands'
		'code' => '61',
	],
	'VA' => [
		'name'   => 'Holy See (Vatican City State)'
		'code' => '39',
	],
	'HN' => [
		'name'   => 'Honduras'
		'code' => '504',
	],
	'HK' => [
		'name'   => 'Hong Kong'
		'code' => '852',
	],
	'HU' => [
		'name'   => 'Hungary'
		'code' => '36',
	],
	'IS' => [
		'name'   => 'Iceland'
		'code' => '354',
	],
	'IN' => [
		'name'   => 'India'
		'code' => '91',
	],
	'ID' => [
		'name'   => 'Indonesia'
		'code' => '62',
	],
	'IR' => [
		'name'   => 'Iran, Islamic Republic Of'
		'code' => '98',
	],
	'IQ' => [
		'name'   => 'Iraq'
		'code' => '964',
	],
	'IE' => [
		'name'   => 'Ireland'
		'code' => '353',
	],
	'IM' => [
		'name'   => 'Isle Of Man'
		'code' => '44',
	],
	'IL' => [
		'name'   => 'Israel'
		'code' => '972',
	],
	'IT' => [
		'name'   => 'Italy'
		'code' => '39',
	],
	'JM' => [
		'name'   => 'Jamaica'
		'code' => '1876',
	],
	'JP' => [
		'name'   => 'Japan'
		'code' => '81',
	],
	'JE' => [
		'name'   => 'Jersey'
		'code' => '44',
	],
	'JO' => [
		'name'   => 'Jordan'
		'code' => '962',
	],
	'KZ' => [
		'name'   => 'Kazakhstan'
		'code' => '7',
	],
	'KE' => [
		'name'   => 'Kenya'
		'code' => '254',
	],
	'KI' => [
		'name'   => 'Kiribati'
		'code' => '686',
	],
	'KR' => [
		'name'   => 'Korea'
		'code' => '82',
	],
	'KW' => [
		'name'   => 'Kuwait'
		'code' => '965',
	],
	'KG' => [
		'name'   => 'Kyrgyzstan'
		'code' => '996',
	],
	'LA' => [
		'name'   => 'Lao People\'s Democratic Republic'
		'code' => '856',
	],
	'LV' => [
		'name'   => 'Latvia'
		'code' => '371',
	],
	'LB' => [
		'name'   => 'Lebanon'
		'code' => '961',
	],
	'LS' => [
		'name'   => 'Lesotho'
		'code' => '266',
	],
	'LR' => [
		'name'   => 'Liberia'
		'code' => '231',
	],
	'LY' => [
		'name'   => 'Libyan Arab Jamahiriya'
		'code' => '218',
	],
	'LI' => [
		'name'   => 'Liechtenstein'
		'code' => '423',
	],
	'LT' => [
		'name'   => 'Lithuania'
		'code' => '370',
	],
	'LU' => [
		'name'   => 'Luxembourg'
		'code' => '352',
	],
	'MO' => [
		'name'   => 'Macao'
		'code' => '853',
	],
	'MK' => [
		'name'   => 'Macedonia'
		'code' => '389',
	],
	'MG' => [
		'name'   => 'Madagascar'
		'code' => '261',
	],
	'MW' => [
		'name'   => 'Malawi'
		'code' => '265',
	],
	'MY' => [
		'name'   => 'Malaysia'
		'code' => '60',
	],
	'MV' => [
		'name'   => 'Maldives'
		'code' => '960',
	],
	'ML' => [
		'name'   => 'Mali'
		'code' => '223',
	],
	'MT' => [
		'name'   => 'Malta'
		'code' => '356',
	],
	'MH' => [
		'name'   => 'Marshall Islands'
		'code' => '692',
	],
	'MQ' => [
		'name'   => 'Martinique'
		'code' => '596',
	],
	'MR' => [
		'name'   => 'Mauritania'
		'code' => '222',
	],
	'MU' => [
		'name'   => 'Mauritius'
		'code' => '230',
	],
	'YT' => [
		'name'   => 'Mayotte'
		'code' => '262',
	],
	'MX' => [
		'name'   => 'Mexico'
		'code' => '52',
	],
	'FM' => [
		'name'   => 'Micronesia, Federated States Of'
		'code' => '691',
	],
	'MD' => [
		'name'   => 'Moldova'
		'code' => '373',
	],
	'MC' => [
		'name'   => 'Monaco'
		'code' => '377',
	],
	'MN' => [
		'name'   => 'Mongolia'
		'code' => '976',
	],
	'ME' => [
		'name'   => 'Montenegro'
		'code' => '382',
	],
	'MS' => [
		'name'   => 'Montserrat'
		'code' => '1664',
	],
	'MA' => [
		'name'   => 'Morocco'
		'code' => '212',
	],
	'MZ' => [
		'name'   => 'Mozambique'
		'code' => '258',
	],
	'MM' => [
		'name'   => 'Myanmar'
		'code' => '95',
	],
	'NA' => [
		'name'   => 'Namibia'
		'code' => '264',
	],
	'NR' => [
		'name'   => 'Nauru'
		'code' => '674',
	],
	'NP' => [
		'name'   => 'Nepal'
		'code' => '977',
	],
	'NL' => [
		'name'   => 'Netherlands'
		'code' => '31',
	],
	'AN' => [
		'name'   => 'Netherlands Antilles'
		'code' => '599',
	],
	'NC' => [
		'name'   => 'New Caledonia'
		'code' => '687',
	],
	'NZ' => [
		'name'   => 'New Zealand'
		'code' => '64',
	],
	'NI' => [
		'name'   => 'Nicaragua'
		'code' => '505',
	],
	'NE' => [
		'name'   => 'Niger'
		'code' => '227',
	],
	'NG' => [
		'name'   => 'Nigeria'
		'code' => '234',
	],
	'NU' => [
		'name'   => 'Niue'
		'code' => '683',
	],
	'NF' => [
		'name'   => 'Norfolk Island'
		'code' => '672',
	],
	'MP' => [
		'name'   => 'Northern Mariana Islands'
		'code' => '1670',
	],
	'NO' => [
		'name'   => 'Norway'
		'code' => '47',
	],
	'OM' => [
		'name'   => 'Oman'
		'code' => '968',
	],
	'PK' => [
		'name'   => 'Pakistan'
		'code' => '92',
	],
	'PW' => [
		'name'   => 'Palau'
		'code' => '680',
	],
	'PS' => [
		'name'   => 'Palestinian Territory, Occupied'
		'code' => '970',
	],
	'PA' => [
		'name'   => 'Panama'
		'code' => '507',
	],
	'PG' => [
		'name'   => 'Papua New Guinea'
		'code' => '675',
	],
	'PY' => [
		'name'   => 'Paraguay'
		'code' => '595',
	],
	'PE' => [
		'name'   => 'Peru'
		'code' => '51',
	],
	'PH' => [
		'name'   => 'Philippines'
		'code' => '63',
	],
	'PN' => [
		'name'   => 'Pitcairn'
		'code' => '870',
	],
	'PL' => [
		'name'   => 'Poland'
		'code' => '48',
	],
	'PT' => [
		'name'   => 'Portugal'
		'code' => '351',
	],
	'PR' => [
		'name'   => 'Puerto Rico'
		'code' => '1',
	],
	'QA' => [
		'name'   => 'Qatar'
		'code' => '974',
	],
	'RE' => [
		'name'   => 'Reunion'
		'code' => '262',
	],
	'RO' => [
		'name'   => 'Romania'
		'code' => '40',
	],
	'RU' => [
		'name'   => 'Russian Federation'
		'code' => '7',
	],
	'RW' => [
		'name'   => 'Rwanda'
		'code' => '250',
	],
	'BL' => [
		'name'   => 'Saint Barthelemy'
		'code' => '590',
	],
	'SH' => [
		'name'   => 'Saint Helena'
		'code' => '290',
	],
	'KN' => [
		'name'   => 'Saint Kitts And Nevis'
		'code' => '1869',
	],
	'LC' => [
		'name'   => 'Saint Lucia'
		'code' => '1758',
	],
	'MF' => [
		'name'   => 'Saint Martin'
		'code' => '1599',
	],
	'PM' => [
		'name'   => 'Saint Pierre And Miquelon'
		'code' => '508',
	],
	'VC' => [
		'name'   => 'Saint Vincent And Grenadines'
		'code' => '1784',
	],
	'WS' => [
		'name'   => 'Samoa'
		'code' => '685',
	],
	'SM' => [
		'name'   => 'San Marino'
		'code' => '378',
	],
	'ST' => [
		'name'   => 'Sao Tome And Principe'
		'code' => '239',
	],
	'SA' => [
		'name'   => 'Saudi Arabia'
		'code' => '966',
	],
	'SN' => [
		'name'   => 'Senegal'
		'code' => '221',
	],
	'RS' => [
		'name'   => 'Serbia'
		'code' => '381',
	],
	'SC' => [
		'name'   => 'Seychelles'
		'code' => '248',
	],
	'SL' => [
		'name'   => 'Sierra Leone'
		'code' => '232',
	],
	'SG' => [
		'name'   => 'Singapore'
		'code' => '65',
	],
	'SK' => [
		'name'   => 'Slovakia'
		'code' => '421',
	],
	'SI' => [
		'name'   => 'Slovenia'
		'code' => '386',
	],
	'SB' => [
		'name'   => 'Solomon Islands'
		'code' => '677',
	],
	'SO' => [
		'name'   => 'Somalia'
		'code' => '252',
	],
	'ZA' => [
		'name'   => 'South Africa'
		'code' => '27',
	],
	'GS' => [
		'name'   => 'South Georgia And Sandwich Isl.'
		'code' => '500',
	],
	'ES' => [
		'name'   => 'Spain'
		'code' => '34',
	],
	'LK' => [
		'name'   => 'Sri Lanka'
		'code' => '94',
	],
	'SD' => [
		'name'   => 'Sudan'
		'code' => '249',
	],
	'SR' => [
		'name'   => 'Suriname'
		'code' => '597',
	],
	'SJ' => [
		'name'   => 'Svalbard And Jan Mayen'
		'code' => '47',
	],
	'SZ' => [
		'name'   => 'Swaziland'
		'code' => '268',
	],
	'SE' => [
		'name'   => 'Sweden'
		'code' => '46',
	],
	'CH' => [
		'name'   => 'Switzerland'
		'code' => '41',
	],
	'SY' => [
		'name'   => 'Syrian Arab Republic'
		'code' => '963',
	],
	'TW' => [
		'name'   => 'Taiwan'
		'code' => '886',
	],
	'TJ' => [
		'name'   => 'Tajikistan'
		'code' => '992',
	],
	'TZ' => [
		'name'   => 'Tanzania'
		'code' => '255',
	],
	'TH' => [
		'name'   => 'Thailand'
		'code' => '66',
	],
	'TL' => [
		'name'   => 'Timor-Leste'
		'code' => '670',
	],
	'TG' => [
		'name'   => 'Togo'
		'code' => '228',
	],
	'TK' => [
		'name'   => 'Tokelau'
		'code' => '690',
	],
	'TO' => [
		'name'   => 'Tonga'
		'code' => '676',
	],
	'TT' => [
		'name'   => 'Trinidad And Tobago'
		'code' => '1868',
	],
	'TN' => [
		'name'   => 'Tunisia'
		'code' => '216',
	],
	'TR' => [
		'name'   => 'Turkey'
		'code' => '90',
	],
	'TM' => [
		'name'   => 'Turkmenistan'
		'code' => '993',
	],
	'TC' => [
		'name'   => 'Turks And Caicos Islands'
		'code' => '1649',
	],
	'TV' => [
		'name'   => 'Tuvalu'
		'code' => '688',
	],
	'UG' => [
		'name'   => 'Uganda'
		'code' => '256',
	],
	'UA' => [
		'name'   => 'Ukraine'
		'code' => '380',
	],
	'AE' => [
		'name'   => 'United Arab Emirates'
		'code' => '971',
	],
	'GB' => [
		'name'   => 'United Kingdom'
		'code' => '44',
	],
	'US' => [
		'name'   => 'United States'
		'code' => '1',
	],
	'UM' => [
		'name'   => 'United States Outlying Islands'
		'code' => '1',
	],
	'UY' => [
		'name'   => 'Uruguay'
		'code' => '598',
	],
	'UZ' => [
		'name'   => 'Uzbekistan'
		'code' => '998',
	],
	'VU' => [
		'name'   => 'Vanuatu'
		'code' => '678',
	],
	'VE' => [
		'name'   => 'Venezuela'
		'code' => '58',
	],
	'VN' => [
		'name'   => 'Viet Nam'
		'code' => '84',
	],
	'VG' => [
		'name'   => 'Virgin Islands, British'
		'code' => '1284',
	],
	'VI' => [
		'name'   => 'Virgin Islands, U.S.'
		'code' => '1340',
	],
	'WF' => [
		'name'   => 'Wallis And Futuna'
		'code' => '681',
	],
	'EH' => [
		'name'   => 'Western Sahara'
		'code' => '212',
	],
	'YE' => [
		'name'   => 'Yemen'
		'code' => '967',
	],
	'ZM' => [
		'name'   => 'Zambia'
		'code' => '260',
	],
	'ZW' => [
		'name'   => 'Zimbabwe'
		'code' => '263',
	],
];