A.To warn people of emergencies via messages
B.To popularize the use of cell phones
C.To estimate the monthly number of messages
D.To promote the wireless industry
A.CTIA
B.the Warning Alert and Response Network
C.FCC
D.federal regulators
A.the US federal government
B.mobile phone users
C.the carriers themselves
D.the law of the United States
A.They must accept the alert service.
B.They may enjoy the alert service for free.
C.They must send the alerts to others.
D.They may choose the types of messages.