I have had an increasing number of robo calls on my Fios Phone line. I called support and was told to register with the Federal Do Not Call list (I did this 3+ years ago). I was told to use nomorobo (I have had this for a year), I was then told to block the calls on the website. I do this as well, but the numbers calling are phantom calls.
Verizon has show no interest in correcting this problem. The representative that I escalated to was unprofessional, dimissive and rude. Verizon charges a premium, which I pay without complaint, but delivers a phone service that is basically a way for telemarketers to lay seige to their customers.
I am contemplating giving up landline service at this point as Verizon seems more interested in ignoring this prolem and scolding their customers for being upset.
If nomorobo can't block the call, NOTE you can ususally tell nomorobo of suspect calls getting through. You can also block normal anonymous and private calls. NoMoRobo is currently the best service to block such calls and way better than any Phone Company offering.
About the only thing you can't block is calls using invalid phone numbers. Verizon use to offer a option "call Intercept" to block such calls, but for some reason does not offer this to new customers any more.
The Do Not Call Registry is a joke. It requires that businesses honor it, and few do.
Nomorobo was the one thing that finally restored peace to my house. Whenever I remember to check the call log, I'll see an average of 25 missed calls each day. That's nomorobo doing its work. Sometimes there will be a day when calls get through, but nomorobo is very quick at updating its database and the calls stop.
However, if calls are regularly slipping through to your house, another option is to puchase CPR V5000 Call Blocker (I'm not affiliated--it was a Christmas Gift). The only bad thing about using Call Blocker is sometimes it takes several seconds to get a dial tone. I occasonally worry about needing to dial 911, but I could always use my mobile phone for emergencies. They have a forum that is monitored by the lead developer, I think. Questions are answered in a timely manner.
My house has one hard wired phone in the cellar (all other phones are wireless). It's become kind of fun to hear that faint ring and then wait to see if the call comes through upstairs. It almost never does.
I also have nomorobo on my iPhone (not free). Robo calls ring and will go to voicemail, but those calls are identified with a nomorobo badge, so I can block them.
Most businesses do honor the "Do not call" list. They can get stiff penalties if they don't. Up to $10000 a call in Florida before any other penalties.
But most of these annoying calls are not from real buisnesses at all and so don't care.
At this time NoMoRoBo is your best protection service.