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Category: Science and Technology
Date Submitted: 06/02/2013 02:48 PM
(TCO B) Explain how SIP sets up and tears down VoIP calls. (Points : 30)
Basic methods used by SIP for setting up and terminating calls are:
REGISTER | | Update Registrar’s database with user’s location |
INVITE | | Call Initiation |
ACK | | Acknowledgement for INVITE/BYE |
CANCEL | | Stop the execution of another command (such as INVITE) |
OPTIONS | | Find out a server’s capability |
BYE | | Terminate a call |
| 1xx | Provisional – indicates that request is being processed |
| 2xx | Success – request was successfully understood and accepted |
| 3xx | Redirection – further action required to complete the request |
| 4xx | Client Error – bad syntax in request or unable to complete the request at this server |
| 5xx | Server Error – server failed to execute a seemingly valid request |
| 6xx | Global Failure – request cannot be completed at any server |
Ganguly, Samrat (04/2011). VoIP - Wireless, P2P and New Enterprise Voice Over IP [1] (VitalSource Bookshelf), Retrieved from http://online.vitalsource.com/books/9781119999256/id/ch05tab01
List and briefly discuss the five types of communication models that VoIP architecture must support
The basic architectural requirements are derived from the deployment scenarios that enable a flexible communication model. Since the VoIP architecture is meant to enable voice calls over a packet-switched IP network such as the Internet, there are certain types of communication model that it must support. These can be listed as:
● Internet-to-Internet: This type of call includes those that originate on a phone connected to the Internet terminate at a phone connected to the Internet and the entire route remains inside the Internet.
● Internet-to-PSTN: These calls have the caller having a phone connected to the Internet whereas the callee is connected to the PSTN. Here the call traverses through both the PSTN segment and the Internet.
● PSTN-to-Internet: In this...