CCrmDocumentCompany::getDocumentName

static function getDocumentName($documentId)
{
	$arDocumentID = self::GetDocumentInfo($documentId);
	$dbRes = CCrmCompany::GetListEx([], ['=ID' => $arDocumentID['ID'], 'CHECK_PERMISSIONS' => 'N'],
		false, false, ['TITLE']
	);
	$arRes = $dbRes ? $dbRes->Fetch() : null;
	return $arRes ? $arRes['TITLE'] : '';
}