QUESTION

a) The handling of the INVITE transaction in SIP is completely different from the handling of other transactions. The handling of the INVITE is one of the most complex aspects of SIP

i) Describe two issues present for the two-way transaction used for non-invite transactions

ii) Explain how the three-way handshake work for the client side

iii) The server side of the INVITE transaction over UDP will retransmit the last provisional response if it receives a retransmitted INVITE request (this means one or more provisional responses have been lost). Explain how does the handling of the final response is different

iv) How is the ACK request formed?