title: Why TLS for SIP
body: <p>Why is TLS the chosen link encryption for SIP?</p>
  
  <p>From a <a href="http://olemartin.com/projects/VPNsolutions.pdf" rel="noreferrer">paper</a>, it seems that TLS can't handle UDP, whereas SIP doesn't require anyone to use TCP alone! So how is the interoperability ensured by TLS!</p>
  
  <p>What would have been the issues if IPSec would have been used instead?</p>