There's more than one way to access the Internet. However, the Copyright Alert System (CAS) applies only to those using landlines. AT&T and Verizon are not applying CAS to the growing number of their customers who use data plans to download materials onto their tablets and smartphones.  

This may seem like a big loophole, but it isn't, because mobile data plans “provide on the order of 100 times less bandwidth than landlines,” says Professor James Grimmelmann of New York Law School. “These plans have caps of 2 to 5 gigabytes per month, while landlines have 250 gigabytes per month.” 

Mobile users thus are limited in the number of infringing files they could download. “The cost of a data plan for large amounts of downloading would suffice to stop large-scale infringement,” Grimmelmann says.