title: [SIP]Response on Receiving 488 (Not Acceptable Here)
body: <p>I am facing an issue regrading the Sip call my flow is as below.</p>
  <ol>
  <li>A Party sends INVITE to SIP agent</li>
  <li>SIP Agent sends INVITE to B party</li>
  <li>B replies with 100 (Trying)</li>
  <li>B sends SIP 488 (Not Acceptable Here)</li>
  <li>Cal Disconected</li>
  <li>Sip Agent sends 488 (Not Acceptable Here) to A</li>
  <li>A Send ACK</li>
  <li>B sends SIP 488 (Not Acceptable Here)</li>
  <li>SIP Agent sends an INVITE</li>
  <li>B sends SIP 488 (Not Acceptable Here)</li>
  <li>SIP Agent sends an INVITE</li>
  </ol>
  <p>in this flow at point 4 B party is sending 488 message, for this B party is expecting an ACK for this.. as we are not sending ACK B party is sending 488 again and again.</p>
  <p>My Question.. is it mandatory that on receiving 488 Error case should we send ACK before disconnecting the call.. if we send ACK will there be any issue.</p>