Wordpress post thumbnail URL

ThumbnailAddress.php

<?php

function ThumbnailAddress( $id = false, $echo = true, $size = "fullsize" ) {
		global $post;
		if( !$id ){
			$thumb = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), $size );
		} else {
			$thumb = wp_get_attachment_image_src( get_post_thumbnail_id($id), $size );
		}
		if( $echo == true ){
			echo $thumb['0'];
		} else {
			return $thumb['0'];
		}
	}
?>