title: Send Multiple Invites with sipsak
body: <p>I'm trying to diagnose an issue with my asterisk server.
  It occurs when INVITEs are sent simultaneously to the server.</p>
  
  <p>I've got the following sipsak command but it only sends one invite, and when I run it multiple times for a bash script, it doesn't seem to have the intended effect.</p>
  
  <pre><code>sipsak --from sip:peer1@127.0.0.1 --auth-username peer1 -v --password 1234 --sip-uri sip:peer1@127.0.0.1 -f testdial1
  </code></pre>
  
  <p>How can I get sipsak to send multiple invites in one go?</p>
  
  <p>Many thanks</p>