title: Passing a variable as an argument using mailcmd in voicemail.conf
body: <p>In my voicemail.conf file, I have a line that looks like this:</p>
  
  <p>mailcmd=php /path/to/file.php 1234</p>
  
  <p>In this case, "1234", which is passed to file.php just fine, is an extension, but frankly, I don't care exactly <em>what</em> gets passed as long as it's something I can use to identify the inbox where the voicemail will get stored.  Because of that, I really need to be able to pass it a variable, like this:</p>
  
  <p>mailcmd=php /path/to/file.php "${VM_NAME}"</p>
  
  <p>When I do that, I get an empty argument in my PHP file.  I've tried a few different channel variables, but I've never gotten anything to work unless the value is hard-coded.</p>
  
  <p>Is it possible to do what I want to do here, and if so, what am I doing wrong?</p>