phone-input-validation.js

var myApp = angular.module('myApp', [])

myApp.directive('phoneValidation', function(){
    return {
        restrict: 'A',
        require: 'ngModel',
        link: function(scope, element, attrs, ngmodel) {

            var newValue;

            scope.$watch(attrs.ngModel, function (value) {
                var newValue = value;
                if (value) {
                    if (value.indexOf('+') === -1) {
                        value = value.replace(/[^0-9+]/g, '')
                    } else if (value.indexOf('+') === 0) {
                        value = '+' + value.replace(/[^0-9]/g, '');
                    } else if(value.indexOf('+') > 0) {
                        value = value.replace(/[^0-9]/g, '');
                    }
                }
                if(newValue !== value) {
                    ngmodel.$setViewValue(value);
                    ngmodel.$render();
                }
            })
        }
    };
});