I have had the same experience as reported by others in 2017, of no caller ID and no message left on answering machine although I'm on the National Do Not Call Directory. I have both a landline and a cell number but I've been getting these calls on the landline. On the ladder I have AT&T call blocking but I'm getting as many as three telemarketing are fraudster/con calls a day, and call blocking only allows 10 calls maximum. So, several times a week I am deleting the oldest in my list and adding the latest. However even doing this some of the robo collar systems or even aggressive telemarketers will just change the last digit of the number and keep calling. That's I would like to know what disconnect/hang up App reporter Spud was referring to and whether it's available only for mobile cell phones or also for landlines. When I have picked up and politely asked to be removed from solicitation list, or press nine to opt out in the majority of the cases, I am not successful. As, if it's person they're not going to take the time to delete you from their Data Bank even if they say they will and opting out option has become a joke! I am averaging 15 calls a week as once your number has been leaked and shared, especially if you are a senior, you are a target, for con artists, so whom are so self-confident, that they will flagrantly leave at 3 minute plus message on your voicemail or answering machine, requesting that you call back for their free service or consultation! The only hope would be for geriatric Geeks, perhaps retired engineers, to create some software to blast them! ;-). This is why I was curious to learn what Spud is utilizing.