Tech Sense October 2026

Stopping Phone SPAM

SPAM, we know them as the messages received over our phones, through our emails, via text messages, and social networks. Some of these are scams attempting to steal money or personal information from innocent people or businesses. 

Telephone SPAM

Last month I conducted a telephone experiment. I forwarded my primary house phone to a different number that went directly to a voice mail account. All incoming phone numbers were also collected and saved. In the first day I received 60 voicemails. Most of these were SPAM with no response. These calls were mostly empty, blank, they varied between two and three seconds to 10, 32 and 52 seconds in duration. I listened to each one and marked each as SPAM, blocking the numbers, preventing them from being called again. There were only two legitimate calls, I saved those messages and returned the calls the next morning. 

Over the past month I have continued this experiment with similar results. I now have a list of over 400 spam callers. My home phone service is provided by Verizon Fios who also provides a SPAM blocking through a company called Nomorobo. This is supposed to block SPAM calls coming to your home phones. So far this hasn’t been effective for me. I am creating a new experiment where I will submit all 400 of these phone numbers to Nomorobo to see if any of them get blocked. 

I also called each of the 60 numbers that called me during the first experiment. It turned out most of them were out of service. Incoming calls to my phone should not have been enabled by any of the North American Phone services. 

Since 2021 the FCC has required all major phone services to use a suite of protocols known as SHAKEN/STIR. STIR stands for Secure Telephone Identity Revisited and it supports Session Initiation Protocol (SIP) used for controlling routes for Voice over Internet Protocol (VoIP) communications. STIR provides information to the receiver for the receiver to confirm the caller.

The SHAKEN system (Signature-based Handling of Asserted information using toKENs) is used for landlines, like your home phone and mobile phone channels. Unfortunately, the SHAKEN system was thought of as a means of verifying Caller ID but what it actually does is verify the original call provider and not the caller.

Stopping the calls

So, you may be wondering how I set this up. It turns out there are several ways that can work. I think the simplest way is to tell Verizon Fios to forward all calls to Voicemail. Most hangups won’t even show up. You can review the remaining calls quickly, deleting the ones that are SPAM. Another means I have used successfully is to forward all calls. I sent all of my calls to a Google Voice number. Then I checked each call. Calls shorter than 4 seconds I immediately delete or I tell Google to mark it as spam. Longer calls I sample to see if I care about the message. Clearly undesirable messages I mark as spam. Any legitimate messages I return a call to the caller that left the voicemail. 

Mobile Phone Call SPAM

Mobile phones are different than the home line. The ability to block SPAM may come from the service provider or from the operating system. Google will even use an AI system to converse with an unrecognized caller and send the information to the recipient. I have even forwarded my home phone to my mobile phone and Google has blocked all of the SPAM phone calls sent to my phone. They also show the calls that were SPAM or were blocked, so I could call them back if I wanted. 

Apple also has built-in call filtering that recognizes many SPAM callers and blocks them. The primary service providers (AT&T, Verizon, and T-Mobile) all offer some form of call filtering. These may have extra costs depending on the provider.

Until Next Time

I plan to cover other SPAM sources and how to block in future columns. For example, to block text messages reply with STOP. This is great to know during election time to block the annoying political advertisements. I will also cover call blockers designed for the home phones and software add-ons for use with your mobile phones.