$re = '/\'.*?\' id=\'phone\$1\'>.*?</';
$str = '<div>
<span class=\'customer\' id=\'phone$0\'>Home</span>
<br/>
<span class=\'customer\' id=\'phone$1\'>Business</span>
<br/>
<span class=\'customer\' id=\'phone$2\'>Mobile</span>
</div>';
$subst = "'customer' id='phone\$1'>Organization<";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php