In a two-way conversation, both sides send and receive data.
Because the two sides must take turns talking, they use the following
protocol:
Only one person can talk at a time.
The person that initiated the conversation talks
first after communication is established.
The person talking must relinquish control before
the other person can speak.
The person with permission to speak is the only
one who can end the conversation.
Figure 2-3 “Two-Way Phone Conversation Without
Confirm” is an illustration of a two-way
conversation without confirm. Because a two-way conversation is
more complex than a one-way conversation, more control information
is needed to manage it.
Figure 2-3 Two-Way Phone Conversation Without
Confirm