Nomorobo First Ring Blocker for Spam Calls

Jim, of the Jim’s Projects blog, uses Nomorobo for his VOIP home phone, and is generally quite happy with the service. One thing that’s not ideal about it though is that while it blocks spammers after the first ring, it still rings one time. Much less annoying than hearing about how you’re in trouble with the IRS — requiring immediate payment via iTunes credit — but annoying nonetheless.

While a Nomorobo first ring blocker has been developed to screen out even these first rings, the bad news is that it doesn’t seem to be available anymore. Naturally, Jim set to work engineering his own blocking method. Theoretically, the single ring could be taken care of via software, but getting the keys to that particular techno-castle is likely a no-go, so Jim instead came up with a hardware solution.

His device uses an Arduino Nano look to for the start of the first ring cycle, then cuts it off with a relay well before it completes even one oscillation. The relay is a DPDT unit wired in parallel, providing some redundancy in the contacts if needed. The it's normally closed, meaning that if the system did loose power, or otherwise stop working, actual calls could get through. This would, unfortunately, also mean a single ring from solicitors. Finally, Jim even added an LCD display on the prototype to log data on blocked calls and see how effective his project has been.