Getting Rid of Many Landline Unwanted Calls

If you have Caller ID service with Verizon (not sure about other companies), you can dial *77 on your phone and you will hear a message that anonymous caller blocking has been enabled. People who call you and block their phone number will hear a message that you do not accept calls from people who block their numbers.

I enabled this feature last month and it dramatically cut down on unwanted callers.