Which cellphone company is best at blocking robocalls?

(CBS) — If you want to stop the spam and scam calls to your cellphone, the carrier you choose matters. That’s the takeaway from a recent study of four major carriers — AT&T, Sprint, Verizon and T-Mobile — which found that most carriers are still poor at identifying spam and scam calls, even when consumers pay for the service.
Cellphone carriers have only had the opportunity to identify and block spam and scam calls for four months. In November, after being flooded wit