DanielKassner.com

<?php
/*
Written by: Daniel Kassner
Website: http://www.danielkassner.com
Originally posted on: http://www.wlscripting.com
Date: 09-13-2007 and last updated: 05-21-2010
*/
if (!function_exists('format_phone_us')) {
	function format_phone_us($phone = '', $convert = true, $trim = true)
	{
		// If we have not entered a phone number just return empty
		if (empty($phone)) {
			return false;
		}

		// Strip out any extra characters that we do not need only keep letters and numbers
		$phone = preg_replace("/[^0-9A-Za-z]/", "", $phone);
		// Keep original phone in case of problems later on but without special characters
		$OriginalPhone = $phone;

		// If we have a number longer than 11 digits cut the string down to only 11
		// This is also only ran if we want to limit only to 11 characters
		if ($trim == true && strlen($phone)>11) {
			$phone = substr($phone, 0, 11);
		}

		// Do we want to convert phone numbers with letters to their number equivalent?
		// Samples are: 1-800-TERMINIX, 1-800-FLOWERS, 1-800-Petmeds
		if ($convert == true && !is_numeric($phone)) {
			$replace = array('2'=>array('a','b','c'),
							 '3'=>array('d','e','f'),
							 '4'=>array('g','h','i'),
							 '5'=>array('j','k','l'),
							 '6'=>array('m','n','o'),
							 '7'=>array('p','q','r','s'),
							 '8'=>array('t','u','v'),
							 '9'=>array('w','x','y','z'));

			// Replace each letter with a number
			// Notice this is case insensitive with the str_ireplace instead of str_replace 
			foreach($replace as $digit=>$letters) {
				$phone = str_ireplace($letters, $digit, $phone);
			}
		}

		$length = strlen($phone);
		// Perform phone number formatting here
		switch ($length) {
			case 7:
				// Format: xxx-xxxx
				return preg_replace("/([0-9a-zA-Z]{3})([0-9a-zA-Z]{4})/", "$1-$2", $phone);
			case 10:
				// Format: (xxx) xxx-xxxx
				return preg_replace("/([0-9a-zA-Z]{3})([0-9a-zA-Z]{3})([0-9a-zA-Z]{4})/", "($1) $2-$3", $phone);
			case 11:
				// Format: x(xxx) xxx-xxxx
				return preg_replace("/([0-9a-zA-Z]{1})([0-9a-zA-Z]{3})([0-9a-zA-Z]{3})([0-9a-zA-Z]{4})/", "$1($2) $3-$4", $phone);
			default:
				// Return original phone if not 7, 10 or 11 digits long
				return $OriginalPhone;
		}
	}
}
?>

<?php
$phone = '1-800-FLOWERS';
echo format_phone_us($phone); // Returns 1(800) 356-9377

$newPhone = format_phone_us($phone, false);
echo $newPhone; // Returns 1(800) FLO-WERS
?>