Voip Tco B

(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...