php check persian and english sms length

checkSMSLength.php

<?php

function checkSMSLength($text) {
    $ucs2 = preg_match('/[^\x00-\x7E]/', $text);
    if (!$ucs2){
        $text = preg_replace('/([[\]{}~^|\\\\])/', "\\$1",$text);
    }

    $strLength = mb_strlen($text);
    $unitLength = $ucs2 ? 70 : 160;

    if ($strLength > $unitLength) {
        $unitLength = $ucs2 ? $unitLength - 3 : $unitLength - 7;
    }

    $count =  max(ceil($strLength / $unitLength), 1);
    $remain = $unitLength * $count - $strLength;

    return [
        'count' => $count,
        'remain' => $remain
    ];
}