title: SIP relay for distributed calling
body: <p>Here is my problem.  I do distributed calling with 10-15 Asterisk boxes.  They each have a different IP address.  My provider wants me to use IP based authentication, which can be a pain (the IP's change on a frequent basis).</p>
  
  <p>I was thinking of setting up one Asterisk box to relay calls from all the others.  That way I'd just need to set up the SIP trunk to the provider on this one box/IP.</p>
  
  <p>Can anyone tell me anything special I would need to do to set this up - either in the dial plan or otherwise?  I do not want all the media to run through the central box, I merely want it to set up the calls and allow the other boxes to talk directly to the provider once the call is set up. </p>
  
  <p>Thanks in advance for any suggestions.</p>