Audio conference call in Skype

1. A is at her PC and she wants to call B, who is also working at his PC. A’s and B’s PCs are both equipped with SIP-based software for making and receiving phone calls. Assume that A knows the IP address of B’s PC. Illustrate the SIP call-establishment process.

2. a. Consider an audio conference call in Skype with N > 2 participants. Suppose each participant generates a constant stream of rate r bps. How many bits per second will the call initiator need to send? How many bits per second will each of the other N – 1 participants need to send? What is the total send rate, aggregated over all participants?

b. Repeat part (a) for a Skype video conference call using a central server.

c. Repeat part (b), but now for when each peer sends a copy of its video stream to each of the N – 1 other peers.