<?php
function check_gsm($str)
{
     $arr = array(
"0x00", "0x01", "0x02", "0x03", "0x04",
"0x05","0x06","0x07","0x08","0x09",
"0x0A","0x0B","0x0C","0x0D","0x0E","0x0F","0x10","0x11","0x12","0x13",
"0x14","0x15","0x16","0x17","0x18","0x19","0x1A","0x1B","0x1B0A",
"0x1B14","0x1B28","0x1B29","0x1B2F","0x1B3C","0x1B3D","0x1B3E",
"0x1B40","0x1B65","0x1C","0x1D","0x1E","0x1F","0x20","0x21","0x22",
"0x23","0x24","0x25","0x26","0x27","0x28","0x29","0x2A","0x2B","0x2C",
"0x2D","0x2E","0x2F","0x30","0x31","0x32","0x33","0x34","0x35","0x36",
"0x37","0x38","0x39","0x3A","0x3B","0x3C","0x3D","0x3E","0x3F","0x40",
"0x41","0x42","0x43","0x44","0x45","0x46","0x47","0x48","0x49","0x4A",
"0x4B","0x4C","0x4D","0x4E","0x4F","0x50","0x51","0x52","0x53","0x54",
"0x55","0x56","0x57","0x58","0x59","0x5A","0x5B","0x5C","0x5D","0x5E",
"0x5F","0x60","0x61","0x62","0x63","0x64","0x65","0x66","0x67","0x68",
"0x69","0x6A","0x6B","0x6C","0x6D","0x6E","0x6F","0x70","0x71","0x72",
"0x73","0x74","0x75","0x76","0x77","0x78","0x79","0x7A","0x7B","0x7C",
"0x7D","0x7E","0x7F");
     $strl = strlen($str);
     for ($i = 0;$i < $strl; $i++)
     {
     $char = '0x' . bin2hex(substr($str,$i,1));
     $pos = in_array($char,$arr);
     if ($pos == 1)
     {
         $j++;
     }
     }
     if ($j < $strl)
     {
     return false;
     }
     else
     {
     return true;
     }
}
?>