How do you stop Robocalls? STIR/SHAKEN Overview

12 August 2021 - 31 min read


Combating Spoofed Robocalls with Caller ID Authentication


In this article, we will be talking about new technology being implemented by the FCC and Congress to reduce those annoying robocalls.

You may have received a call supposedly from the IRS, or your car warranty is about to expire; the list is endless. Most people in the US are tired of these calls, so we are glad that something is finally being done about it. One of the things these callers do is that sometimes they  spoof or fake the number that appears in your Caller ID and use a local area code to get you to answer.

Just so you know… In just the first five months of 2021, we’ve had more than 22 billion robocalls in the US alone. And while there might be some legitimate sales or marketing calls, nearly 2 billion illegal calls are made every month.

Stir Shaken


What is being done about this?

The name of the technology being implemented is STIR/SHAKEN (and I know what you are thinking, but no, it has nothing to do with a nice Martini). For those that want to know the meaning of the term for trivia night, make sure you memorize this:  STIR stands for "Secure Telephone Identity Revisited", while SHAKEN stands for "Signature-Based Handling of Asserted Information Using Tokens Standards".   Ufff, try to say that twice...

Stir Shaken definition

Basically, this means that as calls travel through the phone network, their Caller ID is signed as legitimate by originating carriers and phone companies before reaching their destination. And don’t worry, this all happens in milliseconds, so it doesn't cause a delay in the call.

STIR/SHAKEN technology is designed to protect you from robocalls increasingly, the way that ANTI-SPAM solutions were implemented to protect your email inbox from unwanted emails, aka SPAM emails. It’s a filtering and authentication system.


What does this mean to you as a user of telephone services?


Purchase Phone

The deadline for telephone providers to implement this technology was June 30th, 2021, and the goal is to share the positive news of this effort and make you aware of some growing pains you may feel along the way.

This system uses digitally signed secure certificates to authenticate known companies and phone numbers, and uses A, B, or C rating system called attestation.


In some situations, you can encounter unverified callers that this new technology will not be able to validate. As a result, calls might not get through, and the caller will experience one of 3 symptoms:

The call will sound busy.
The call will ring non-stop, without ever reaching voicemail.
The call will go straight to voicemail.

If you or someone trying to call you do experience any of these three scenarios over the next few months, it may not be a problem directly related to GreenLink services themselves but false positives of this new technology. We may need a call sample, including the date and time of the call, and involved phone numbers for us to escalate to our underlying carriers. It is possible that the caller needs to verify with their phone company that they are fully verified and calls carry that certificate.

The GreenLink service, and phone numbers provided with the service or phone numbers ported to our service, are already being signed automatically with complete or “A” attestation. This lowers the chance that calls originating from GreenLink will be blocked by a terminating carrier.



MarketingFeel free to contact us if you experience any of these scenarios or if you would like to get more details on the topic!

Reach out to us  888-972-8802 or by dialing *611 from any GreenLink phone or softphone.



We will help you on this journey!

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