Correct me if I'm wrong - but placing a load and seizing the line immediately (milliseconds?) after sensing the 1st ring will cause the off-hook condition thus preventing the caller-ID to be sensed?
Not quite right. If you look at the circuit of a phone, when the handset is on the phone (hung up) the switch that connects it to the incoming line is open so the line voltage (about 48VDC) is not getting to the phone. However, there is a capacitor across the switch that allows the AC ring signal and the caller ID tones to bypass the open switch. The off hook condition will not occur until that switch closes and the phone starts to draw current from the DC voltage.
A micro controller would monitor the incoming line for AC ring tones and once the first ring is done it would then look for the caller ID modem tones. At that point the micro would decide if it should connect the incoming line to the phones based on the caller ID info. If the line is connected to the phones at that point the second and subsequent ring tones would go to the house phones since no DC connection has been made yet. The micro has only monitored the AC signals through a capacitor.
We use a Digitone Call Blocker. Cost something less than $100. You put it between the incoming line and the phone(s) you don't want to ring. If the caller ID is on its list, it blocks the call and hangs up after one ring. If the number is not on the list, it connects the line and your phone rings on the second ring. You can program it to reject all calls with no caller ID. It is easy to add numbers to the blocked list. You can block up to 70-odd numbers which has been enough for us for about a year now.
That being said, the sad truth is: Blockers based on caller ID are not going to work very much longer because the BadGuys will change and/or "spoof" (which really means Lie about) their number. Sooner or later perhaps Congress will pass a law with some teeth in it, but for now it is an arms race.
But for now it sure does my heart good to hear the phone in the bedroom ring once and see a number show up on the Dish and nothing else happen!
Can you block all 800 prefix calls, or all out of area code calls? This would likely be considered the ability to enter wildcard listing such as 800 ??? ???? on your block list.
Can you block all 800 prefix calls, or all out of area code calls? This would likely be considered the ability to enter wildcard listing such as 800 ??? ???? on your block list.
Since I use Skype as my primary phone I can use a nice feature of Skype. You can put a call on hold. And your phone works as good as before. Even multiple calls can be on hold without problems.
And that is what I do. I put them on hold until they hang up. As long as they are on hold with my phone they can't bother anybody else.
Do any robocalls actually originate from 800 numbers? I always thought that was a toll-free routing alias for when you called them.
The same one that keeps calling me at least 4 times every day is from 800 number.
It's a robot for sure as there's never a life person on the other end - just silence.
My ISP, (Comcast-Optimum) also lets me to create my own black list. Has worked very well for the last two years. Only have to update every once in a while when the callers change their numbers.
Of course you have to have their internet phone service.
Comments
... or they might do this http://en.wikipedia.org/wiki/Caller_ID_spoofing
although that is against http://www.fcc.gov/guides/caller-id-and-spoofing
One of the entries https://www.youtube.com/user/ThePhoneCop was highlighted by parallax
" TPC was selected by Parallax as their 'Project of the Week' for Wednesday, February 20, 2013.
https://www.youtube.com/redirect?q=http%3A%2F%2Fwww.parallax.com%2FHome%2FParallaxRSSFeed%2Ftabid%2F761%2FDefault.aspx&redir_token=5oZYWUdLtC8XG0A9ysL5dSvIa2B8MTM5NjM2NzI1M0AxMzk2MjgwODUz "
but that link is not there anymore. Why?
Not quite right. If you look at the circuit of a phone, when the handset is on the phone (hung up) the switch that connects it to the incoming line is open so the line voltage (about 48VDC) is not getting to the phone. However, there is a capacitor across the switch that allows the AC ring signal and the caller ID tones to bypass the open switch. The off hook condition will not occur until that switch closes and the phone starts to draw current from the DC voltage.
A micro controller would monitor the incoming line for AC ring tones and once the first ring is done it would then look for the caller ID modem tones. At that point the micro would decide if it should connect the incoming line to the phones based on the caller ID info. If the line is connected to the phones at that point the second and subsequent ring tones would go to the house phones since no DC connection has been made yet. The micro has only monitored the AC signals through a capacitor.
Is this the link you are looking for: https://www.youtube.com/watch?v=CWiP5Q82SDg? I found it on this page: http://robocall.challengepost.com/submissions/13334-the-phone-cop.
— David Carrier
Parallax Inc.
DAvid, I thought that you were going to point me to the original (and still accessible) parallax Project of the Week link instead...
"Thanks go out to Parallax for selecting my entry as their 'Project of the Week' for Wednesday, February 20, 2013.
https://www.parallax.com/Home/ParallaxRSSFeed/tabid/761/Default.aspx?ItemId=764"
as his link above does not work anymore
That being said, the sad truth is: Blockers based on caller ID are not going to work very much longer because the BadGuys will change and/or "spoof" (which really means Lie about) their number. Sooner or later perhaps Congress will pass a law with some teeth in it, but for now it is an arms race.
But for now it sure does my heart good to hear the phone in the bedroom ring once and see a number show up on the Dish and nothing else happen!
Or does it just require specific numbers?
You can block by area code.
And I do no remember any robocalls from there.
Since I use Skype as my primary phone I can use a nice feature of Skype. You can put a call on hold. And your phone works as good as before. Even multiple calls can be on hold without problems.
And that is what I do. I put them on hold until they hang up. As long as they are on hold with my phone they can't bother anybody else.
Enjoy!
Mike
The same one that keeps calling me at least 4 times every day is from 800 number.
It's a robot for sure as there's never a life person on the other end - just silence.
Of course you have to have their internet phone service.