Many people have registered with the FTC National Do Not Call Registry, however it will not stop all unwanted calls. The “Do Not Call” registry prohibits sales calls so you may still receive political, charitable, debt collection and informational calls, as well as telephone survey calls. In addition, companies may still call if you have recently done business with them or if you have given written permission to call you. If you ask a company not to call you again, it must honor your request. ( record the date of your request).
There is also a website, www.nomorobo.com where you can register your landline phone for free that will stop most robocalls that you still might get after registering with the FTC. If a robocaller dials your number, your phone will ring once and Nomorobo will intercept the call.
A mobile application for your cell phone is available for $1.99 a month, but there is no charge to register a regular landline phone.
P.S. I have used Nomorobo on my own landline and it works like a charm. One ring and Nomorobo intercepts the call.