"Ninety-nine dollars is a bit steep for a lot of people," Dulaney said. "But these plans are definitely another step toward the replacement of wired phones with wireless phones."
At $100 a month, "you won't see big changes," Kerton said. "At $60, all kinds of people will drop their land lines."
Another reason that flat-rate plans will encourage abandonment of land lines is that younger subscribers don't necessarily expect to have land lines.
"Most [young people] today grew up with wireless phones," Dulaney said. "They're more used to wireless. It's the kind of thing the younger generation wants. They're done with wires."
He added that, besides lower-cost flat-rate plans, the other thing necessary for this trend to take off is more widespread availability of femtocells, which are router-size boxes that boost indoor reception of cellular signals. A handful of cellular operators, including Sprint in the U.S., are starting to sell femtocells, and more carriers are expected to start making them available later this year.