title: +CME ERROR: 100 when executing USSD command in perl
body: <p>I'm using this script to check the credit on my SIM card using USSD command it works fine using a an old Nokia phone connected with USB cable to my PC , the issue is the same script is not working when I use this device : <br>
  <a href="https://i.stack.imgur.com/WZoqj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WZoqj.png" alt="Huawei USB device" /></a> ,<br> what possibly might be wrong ? here is my Perl script and please note that communication is working fine through the COM7 port:</p>
  <pre><code>    use strict;
      use Win32::SerialPort 0.11;
      my $ob = Win32::SerialPort-&gt;start (&quot;config.cfg&quot;) || die;
      $ob-&gt;write(&quot;AT+CUSD=1,\&quot;*200#\&quot;,15&quot;);
      sleep 5;
      my $credit = $ob-&gt;input;
      my($directory) = $credit =~ /(.*) DA/;
      print &quot;$directory\n&quot;;
  </code></pre>
  <p>my configuration file <code>config.cfg</code>:</p>
  <pre><code>Win32::SerialPort_Configuration_File -- DO NOT EDIT --
  \\.\COM7
  CFG_1,none
  eol,10
  clear,-@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@-
  RCONST,0
  istrip,0
  CFG_2,none
  XOFFCHAR,0
  PARITY_EN,0
  WCONST,200
  intr,3
  U_MSG,1
  STOP,1
  XONLIM,0
  erase,8
  XONCHAR,0
  BINARY,1
  RTOT,0
  echonl,0
  XOFFLIM,0
  icrnl,0
  inlcr,0
  READBUF,2097152
  igncr,0
  EOFCHAR,0
  WRITEBUF,0
  RINT,4294967295
  ocrnl,0
  bsdel, 
  opost,0
  echoke,1
  PARITY,none
  HNAME,localhost
  echoctl,0
  CFG_3,none
  EVTCHAR,0
  icanon,0
  isig,0
  HADDR,0
  E_MSG,1
  DATA,8
  DVTYPE,none
  echo,0
  quit,4
  s_eof,26
  s_kill,21
  ERRCHAR,0
  onlcr,1
  ALIAS,COM7
  HSHAKE,rts
  DATYPE,raw
  echok,1
  echoe,1
  BAUD,9600
  WTOT,10
  </code></pre>