Convert Phone Word to Phone Number

functions.php

<?php
/**
 * Convert a phone number containing words, to a plain number. e.g. '1800 CALLME' == '1800225563'
 */
function ephemeris_phone_word_to_number( $phone_number ) {
	$phone_word_pattern = array(
		'a' => '2',
		'b' => '2',
		'c' => '2',
		'd' => '3',
		'e' => '3',
		'f' => '3',
		'g' => '4',
		'h' => '4',
		'i' => '4',
		'j' => '5',
		'k' => '5',
		'l' => '5',
		'm' => '6',
		'n' => '6',
		'o' => '6',
		'p' => '7',
		'q' => '7',
		'r' => '7',
		's' => '7',
		't' => '8',
		'u' => '8',
		'v' => '8',
		'w' => '9',
		'x' => '9',
		'y' => '9',
		'z' => '9',
		' ' => '',
		'-' => '',
		'(' => '',
		')' => '',
		'[' => '',
		']' => '',
	);

	if( !empty( $phone_number ) ) {
		return str_ireplace( array_keys( $phone_word_pattern ), array_values( $phone_word_pattern ), $phone_number );
	}

	return false;
}