title: "s" as a starting extension not working in Asterisk dial plan
body: <p>I have</p>
  
  <pre><code>  [from-pstn]
    exten =&gt; s,1,Playback(demo-thanks) 
  </code></pre>
  
  <p>as the first line in the context of a dialplan. It does not work.</p>
  
  <p>However, when it is replaced by this:  </p>
  
  <pre><code>  [from-pstn]
    exten =&gt; _X.,1,Playback(demo-thanks)
  </code></pre>
  
  <p>It works. Is the "s" extension not the start extension? </p>
  
  <p>This is the dialplan on a PRI line. When the caller calls in, the first line in the [from-pstn] context is triggered. The "front-pstn" context is referenced in dahdi.conf. That is not the source of the problem as it would not have worked with the _X. extension.</p>
  
  <p>I am just starting to write Asterisk dialplans. </p>