Are your children getting text-message spam on their cellphones (or are you) – those annoying messages that you can't delete without opening them and that you, not the sender, pay for? Well, there's hope, or help, rather, David Pogue at the New York Times reports. AT&T and Verizon Wireless let you block spam messages. Sprint and T-Mobile "don't go quite as far," Pogue writes, "but they do offer some text-spam filtering options." In his Circuits column, he explains how cellphone spamming works and where to find each cellphone company's spam controls. See also Forbes on "Cellphone Addiction" (more about grownups, though).