First, what is the definition of network externalities? Second, think about your phone. Imagine the situation where you could only call/text/contact other people who have the SAME phone provider you have: Verizon customers can only contact other Verizon customers; Sprint customers can only contact other Sprint customers, etc. What exactly does that have to do with network externalities? And third, would you be willing to operate under that scenario (Verizon-people-can-only-call-Verizon-people) if it meant your phone bill was cut in half every month? Why or why not?