PHP function to make mobile numbers in full international format

mobile-number-formatter.php

<?php
/**
 * Formats mobile numbers as international.
 *
 * @access public
 * @param string $number is a mobile phone number
 * @param array $args is an associative array of variables (see $defaults)
 * @return string
 */
 
function format_mobile_as_international( $number, $args=null ) {
	$defaults = array(
		'Country Code' => '966', // (966) 555555555
		'Local Prefix' => '0',   // (0) 555555555
		'First Digit' => '5', // 0 (5) 55555555
		'IDD' => '00', // (00) 966 555555555 
		'Local Length' => 10 // length as dialled locally e.g. 0555555555 = 10 digits
	);
	$args = array_merge( $defaults, (array) $args );
	
	// only keep digits: no spaces, dashes, plus signs, etc.
	$number = preg_replace( "/[^0-9]/", "", $number ); 
	
	// Phone number is like 0555555555	
	if ( $number[0] == $args['Local Prefix'] && strlen( $number ) == (int) $args['Local Length'] ) {
		$number = substr( $number, strlen( $args['Local Prefix'] ) );
		$result = $args['Country Code'] . $number;
	}
	// Phone number is like 555555555
	elseif ( $number[0] == $args['First Digit'] && strlen( $number ) == (int) $args['Local Length'] - strlen( $args['First Digit'] ) ) {
		$result = $args['Country Code'] . $number;
	}
	// Phone number is like 00966555555555
	elseif ( substr( $number, 0, strlen( $args['IDD'] ) ) == $args['IDD'] && strlen( $number ) == (int) $args['Local Length'] - strlen( $args['Local Prefix'] ) + strlen( $args['IDD'] ) + strlen( $args['Country Code'] ) ) { 
		$result = substr( $number, strlen( $args['IDD'] ) );
	} 
	// Phone number is like 966555555555
	elseif ( substr( $number, 0, strlen( $args['Country Code'] ) == $args['Country Code'] && strlen( $number ) == (int) $args['Local Length'] - strlen( $args['Local Prefix'] ) + strlen( $args['Country Code'] ) ) { 
		$result = $number;
	} 
	// else omit
		
	return $result;
}

echo format_mobile_as_international("00966555555555");
?>