Sorry to bear sad tidings, but your car’s extended warranty is about to expire. At least that’s what you’ll likely hear if you answer one of those robocalls that have descended like a plague upon us. We applaud any effort to control the flood of robocalls, even if it means supplementing a commercial blocking service with a DIY ring-blocker.
The commercial service that [Jim] engaged to do his landline blocking is called Nomorobo – get it? It uses the Simultaneous Ringing feature many VoIP carriers support to intercept blacklisted robocallers, but with a catch: it needs caller ID data, so it lets the first ring go through. [Jim]’s box intercepts the ringing signal coming from his Xfinity modem using a full-wave rectifier and an analog input on an Arduino. Once the ring pattern is received, the Arduino flips a relay that connects all the phones in the house to the line, letting the call ring through. If Nomorobo has blocked the call, he’ll never hear a thing. There were a few glitches to deal with, like false positives from going off- and on-hook, but those were handled in software. There’s also a delay in displaying caller ID information on his phones, but it’s a small price to pay for peace.
Any escalation in the war on robocalls is justified, and we applaud [Jim] for his service. Should you feel like joining the fray, step one is to know your enemy. This primer on robocalling will help.
Thanks to [Phil] for the tip.
Despite the implementation of the National Do Not Call Registry in the US (and similar programs in other countries), many robocallers still manage to get around the system. Whether they’re operating outside the law somehow (or they simply don’t care about it) there are some ways you can take action to keep these annoying calls from coming through. [Alex] is among those to take matters into his own hands and built a specialty robocall-blocking device.
Based on a Raspberry Pi, the “Banana Phone” is able to intercept incoming calls on standard land lines or VoIP phones. After playing a short message, the caller is asked to input a four-digit code. Once the code is correctly entered, the caller is presumed to be human, added to a whitelist, and then the Pi passes them on to the recipient. There are, however, some legitimate robocallers such as emergency services regarding natural disasters or utility companies regarding outages. For these there is a global whitelist that the Pi checks against and forwards these robocalls on to the recipient automatically.
This project was originally an entry into a contest that the Federal Trade Commission put on a few years ago for ideas about how to defend against robocalls. We covered it back then, but now there are full build instructions. Even though the contest is long over, the Banana Phone is still in active development so if you have a spare Pi lying around you can still set this up yourself. There are some other interesting ways to defend against robocalls as well, like including the “line disconnected” tone in your voicemail, for example.
The Federal Trade Commission really doesn’t like robocalls and other telephone solicitors selling you vinyl siding or home security upgrades. The FTC is even offering $50,000 to anyone who can do away with these robocalling telemarketers, and [Alex] looks like he might just claim the prize. He developed The Banana Phone, a device that eliminates those pesky telemarketers.
The basic idea of the Banana Phone is requiring callers to enter a four-digit pass code (played via text to speech over a relevant song to prevent a bot from getting through) before connecting them to the main line. Once a caller has been verified as human, their number is added to a white list so they won’t have to listen to [Raffi] every time they call.
The Banana Phone uses off-the-shelf parts including a Raspberry Pi and a phone/Ethernet adapter with the total build cost under $100. You can check out a demo of the Banana Phone in action after the break starting at about 2:25.
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