It never fails: Just as you sit down to enjoy a nice meal with the family, your phone rings. Sigh. Even more annoying is the fact that a glance at your smartphone screen doesn’t show who’s calling.

Adam B calls numbers you should never dial.

The FBI has just warned that Americans lost more than $16 billion last year, up more than 30% on the year before. The plague of scams targeting phones and computers by email and text message topped ...