title: calling a sip phone
body: <p>im searching for a simple method to "ping" a sip:user@ip and get back a status like "available for call" , "busy" , "not connected" if the first two require to make his phone ring, thats ok
  (optionally if necessary to call them to see the status then it was nice to include a senders number so that i can identify my server on the phone display when its checking the status or to play a short signal .wav in case someone takes up, so that they know what it was)</p>
  
  <p>.....something like  sipsak -x 1200 -C random@ownip -s sip:adressee@hisip -vvv...<br>
  gives me "406 Not Acceptable without Contact header"
  i did not try anything else yet
  i already wonder if the sending call still needs to be logged in at an isp then?</p>