title: What is the difference between "P-Asserted-Identity" and "P-Called-Party-ID"?
body: <p>Please explain the scenario with an example which has both the ids are different in a single SIP session.</p>
  
  <p>Along with it also explain in <a href="https://en.wikipedia.org/wiki/IP_Multimedia_Subsystem" rel="nofollow noreferrer">IMS</a> network who fills the "P-Called-Party-ID" (is it P-CSCF / S-CSCF session manager).</p>