SSCA Session Management 2

Question 1

Which SIP method is used to re-negotiate the parameters of an existing session without terminating it?

Accepted Answer

re-INVITE

Answer

A re-INVITE is sent within an established dialog to modify session parameters such as codecs, media addresses, or to place a call on hold.

Question 2

What is the purpose of the UPDATE method in SIP session management?

Accepted Answer

To modify session parameters before or during a session without changing the dialog state

Answer

The UPDATE method (RFC 3311) allows a UAC to modify session parameters mid-call without affecting the dialog state, unlike re-INVITE.

Question 3

When a SIP session is placed on hold using RFC 3264, what value is set in the SDP 'c=' line or 'a=' attribute?

Accepted Answer

c=0.0.0.0 or a=sendonly

Answer

RFC 3264 specifies that hold is indicated by setting the connection address to 0.0.0.0 or by using the 'a=sendonly' attribute in the SDP offer.

Question 4

Which SIP header field uniquely identifies a dialog and is used to match subsequent requests to an established session?

Accepted Answer

The combination of Call-ID, From tag, and To tag

Answer

A SIP dialog is uniquely identified by the triple: Call-ID, the From tag, and the To tag, which together distinguish it from all other dialogs.

Question 5

What happens to a SIP session if a re-INVITE is rejected with a 488 Not Acceptable Here response?

Accepted Answer

The original session parameters remain in effect

Answer

If a re-INVITE is rejected, the original session parameters negotiated during the initial INVITE remain in effect and the session continues unchanged.

(SSCA) Sip School Certified Associate Practice Test

(SSCA) Sip School Certified Associate Practice Test

SSCA Session Management 2