$3.(15$ points$)$ Consider an audio application that sends a VoIP payload $($G$\mathrm{.}711$ formatted audio message$)$ using a network

packet, where the layers and fields of the packet are shown in the figures below.

$2$ of $4$

The resulting packet to be transmitted is:

a$.$ How many overhead bytes does each packet include?

b$.$ Suppose the voice payload is $640$ Bytes. What is the frame efficiency of the packet?

c$.$ Suppose we want the voice payload to be large enough so that the overhead is at most $20\%$ of the total,

how many audio bytes must each packet carry?