SSCA SIP Troubleshooting & Diagnostic Tools 5

Question 1

What does a '487 Request Terminated' response indicate in a SIP transaction?

Accepted Answer

The INVITE was terminated by a CANCEL before it was answered

Answer

487 Request Terminated is the final response to an INVITE that was cancelled by the UAC using a CANCEL method.

Question 2

During SIP troubleshooting, the 'Record-Route' header is used to:

Accepted Answer

Force subsequent in-dialog requests through specific proxies

Answer

Record-Route causes proxies to insert themselves into the dialog path so that all in-dialog requests (like re-INVITEs and BYE) pass through them.

Question 3

Which tool can be used to simulate SIP load by generating thousands of simultaneous SIP calls for stress testing?

Accepted Answer

SIPp

Answer

SIPp is a performance testing tool that can simulate thousands of simultaneous SIP UAC/UAS scenarios with detailed statistics.

Question 4

A SIP re-INVITE is sent mid-call. Which scenario would NOT require a re-INVITE?

Accepted Answer

Requesting a new call-ID for the session

Answer

The Call-ID identifies a dialog and cannot be changed mid-call; hold, codec changes, and stream additions all legitimately trigger re-INVITEs.

Question 5

When a SIP proxy returns '301 Moved Permanently', what action should the UAC take?

Accepted Answer

Send the request to the new address in the Contact header and update stored location

Answer

301 Moved Permanently tells the UAC to redirect the request to the URI in the Contact header and permanently store the new address.

(SSCA) Sip School Certified Associate Practice Test