STIR/SHAKEN is transforming how phone calls work—and not everyone benefits. Here’s what outbound sales teams need to know to protect their connect rates.

Your sales rep dials a qualified prospect. The phone rings. But on the prospect’s screen, instead of your company name, they see “Scam Likely” flashing in red letters. They don’t answer. Your call goes straight to voicemail, and your perfectly legitimate business opportunity dies before it even starts.

This isn’t a rare occurrence anymore—it’s happening to outbound sales teams across the country, multiple times per day. And in many cases, the culprit is a system called STIR/SHAKEN.

You might have heard the acronym thrown around in industry conversations or seen it mentioned in your carrier’s terms of service. But what actually is STIR/SHAKEN? More importantly, how does it affect your ability to reach prospects on the phone?

The short answer: STIR/SHAKEN is a call authentication framework designed to combat caller ID spoofing and robocalls. The system verifies that the phone number showing up on caller ID is actually the number making the call. It’s a good idea in theory—stopping scammers from pretending to be your bank or the IRS.

But in practice, STIR/SHAKEN has created serious challenges for legitimate businesses that rely on outbound calling. Understanding how the system works is essential for protecting your connect rates and maintaining a successful sales operation.

In this guide, we’ll break down exactly what STIR/SHAKEN is, how the authentication process works, why it’s causing your calls to get flagged, and—most importantly—what you can do to ensure your legitimate sales calls get through to prospects.

At Call Logic, we help sales teams navigate these technical challenges every day. Let’s dive in.

Call Logic’s power dialer helps you maintain proper call authentication and protect your caller ID reputation. Call for your free consultation today to learn how we keep your calls connecting!

What STIR/SHAKEN Is and Why It Exists

STIR/SHAKEN isn’t a cocktail—it’s a mouthful of an acronym that stands for two separate but related protocols:

STIR: Secure Telephone Identity Revisited
SHAKEN: Signature-Based Handling of Asserted Information Using tokens

Together, they form the STIR SHAKEN framework that authenticates caller ID information before calls reach their destination.

Preventing Spoofed Calls

The primary purpose of STIR/SHAKEN is to combat caller ID spoofing—the practice of making a phone call appear to come from a different number than it actually does.

Scammers have used spoofing for years to trick people into answering their calls. They might make their number look like it’s from:

A local area code (neighbor spoofing)
A government agency like the IRS
A well-known business like your bank
Even your own phone number

By making the call appear legitimate, scammers dramatically increase their answer rates. And once someone picks up, they can deploy their social engineering tactics to steal money or personal information.

Spoofed calls aren’t just annoying—they’re a massive problem that costs Americans billions of dollars annually in fraud losses.

Role of the FCC

The Federal Communications Commission (FCC) recognized that caller ID spoofing was out of control. Existing regulations weren’t enough to stop it because the underlying phone infrastructure had no built-in way to verify that caller ID information was accurate.

In 2019, the FCC passed rules requiring voice service providers to implement STIR/SHAKEN in their networks. The deadlines rolled out in phases:

June 2021: Large providers had to implement STIR/SHAKEN
June 2022: Smaller providers and intermediate providers followed
June 2023: All remaining providers were required to comply

The goal was simple: make it technically impossible to spoof caller ID without detection. If every call carrier proper authentication, spoofed calls would be identified and blocked before reaching consumers.

Authentication of Caller ID Information

At its core, STIR/SHAKEN works by having the originating phone carrier digitally sign outbound calls to verify that the caller ID information is accurate and hasn’t been tampered with.

When a call travels through the phone network, each carrier along the path can check this digital signature. If the signature is valid, the call is authenticated and more likely to go through. If the signature is missing or invalid, the call might get flagged as potential spam or fraud.

For legitimate businesses, this should be a good thing—your calls are authenticated, proving you’re not spoofing your caller ID. But as we’ll see, the reality is more complicated.

How STIR/SHAKEN Works

Understanding the technical mechanics of STIR/SHAKEN helps explain why some calls get through while others get blocked. Let’s break down the authentication process.

SIP Headers

STIR/SHAKEN works through Session Initiation Protocol (SIP)—the technology that handles call setup on modern digital phone networks.

When you make a call, your carrier adds authentication information to the SIP headers—essentially metadata that travels along with the call. This information includes:

A digital signature proving the caller ID is legitimate
An attestation level (which we’ll cover shortly)
Information about which carrier verified the call

Think of it like a digital seal of authenticity attached to your call. As the call moves through the network, other carriers can check this seal to verify the call is legitimate.

The Verification Process

Here’s what happens when you make an outbound call in a STIR/SHAKEN-enabled network:

Step 1: Call Origination You place a call from your business phone number. Your VoIP provider or carrier receives the call request.

Step 2: Authentication Your carrier checks whether they can authenticate the caller ID. They verify:

Do they have the authority to use this phone number?
Is the caller ID information accurate?
What level of confidence can they assign to this call?

Step 3: Signing Based on their verification, the carrier adds a digital signature to the SIP headers along with an attestation level (A, B, or C—more on these shortly).

Step 4: Transmission The call travels through the phone network to the destination carrier.

Step 5: Verification The receiving carrier checks the digital signature. If it’s valid and the attestation level is high, the call proceeds normally. If something looks wrong—missing signature, low attestation, tampered headers—the call may get flagged or blocked.

Step 6: Delivery The call reaches the recipient’s phone, potentially with a label attached based on the authentication results.

This all happens in milliseconds, completely invisible to the caller and recipient—unless something goes wrong.

IP vs. Non-IP Networks

Here’s where things get tricky for many businesses: STIR/SHAKEN only works on IP-based phone networks.

IP Networks: Modern VoIP systems and digital carriers can implement STIR/SHAKEN because they use SIP headers to route calls. These networks support the digital signatures required for authentication.

Non-IP Networks: Traditional landlines and some older phone systems don’t use SIP. They can’t carry the authentication information required by STIR/SHAKEN.

What happens when a call crosses between IP and non-IP networks? The authentication information might be lost or downgraded. This is one reason why some legitimate calls end up with poor attestation levels even when nothing is actually wrong.

If your business is still using traditional phone lines for outbound calling, you’re at a disadvantage in the STIR/SHAKEN era. Moving to a modern VoIP-based system is essential for maintaining good call authentication.

Understanding Attestation Levels (A, B, and C)

Not all authenticated calls are created equal. The STIR/SHAKEN framework uses three attestation levels to indicate how confident the carrier is that the caller ID information is legitimate.

Full Attestation (Level A)

Level A—also called “Full Attestation”—is the gold standard. It means the originating carrier:

Verified they are authorized to use the phone number
Confirmed the caller ID matches the actual calling party
Has direct knowledge that the call is legitimate

To get A-level attestation, you typically need to:

Own or lease the phone number directly from your carrier
Use a carrier that can verify your identity as a business
Make calls through a properly configured system

Calls with A-level attestation are least likely to be flagged as spam. They pass through carrier filters with minimal scrutiny and generally display properly on recipient phones.

If you’re serious about outbound sales, A-level attestation should be your goal. It’s the closest thing to a “verified caller” badge in the current phone system.

Partial Attestation (Level B)

Level B—”Partial Attestation”—means the carrier verified some information but not everything. Specifically:

They confirmed they’re authorized to use the phone number
But they can’t fully verify the caller’s identity

This often happens when:

You’re using a number through a reseller or third-party service
Your carrier doesn’t have direct verification of your business identity
The call is routing through multiple carriers before reaching the destination

B-level attestation is better than nothing, but it puts your calls at higher risk of being flagged. Some carrier spam filters treat B-level calls with more suspicion, leading to lower connect rates.

Gateway Attestation (Level C)

Level C—”Gateway Attestation”—is the lowest level. It means:

The carrier is allowing the call to pass through
But they cannot verify the caller ID information at all

C-level attestation typically occurs when:

Calls cross from IP to non-IP networks
The originating carrier doesn’t participate in STIR/SHAKEN
The authentication information was lost or corrupted in transit

Gateway attestation offers almost no protection against spam labeling. In fact, many carriers treat C-level calls as high risk by default. Your calls are much more likely to be blocked or labeled as “Scam Likely” with C-level attestation.

If your calls are getting C-level attestation, you need to fix your carrier relationship or phone system configuration immediately. Operating at Level C is a recipe for terrible connect rates.

Why Outbound Sales Teams Are Affected

STIR/SHAKEN was designed to stop scammers, not hurt legitimate businesses. So why are sales teams suffering? Let’s talk about the unintended consequences.

The “Scam Likely” and “Potential Fraud” Labels

When a call has poor attestation or fails authentication checks, carriers and spam detection apps slap warning labels on it. Recipients see things like:

“Scam Likely“
“Spam Risk”
“Potential Fraud”
“Unknown Caller”

These labels are devastating for sales teams. Research shows that answer rates drop by 70% or more when calls display spam warnings. Even interested prospects won’t pick up when they see these labels.

The problem is that STIR/SHAKEN creates a binary outcome for many carrier spam filters: calls are either properly authenticated or they’re suspicious. There’s not much middle ground. And if your calls fall into the “suspicious” category—even for technical reasons that have nothing to do with your actual business practices—you get hit with spam labels.

For more detailed information about why your calls might be getting blocked and what you can do about it, check out our guide on why outbound sales calls get blocked.

Devastating Drop in Connect Rates

Let’s talk numbers. Before STIR/SHAKEN implementation, a well-run outbound sales team might see connect rates of 10-15%. Not great, but workable.

After STIR/SHAKEN, teams with poor attestation levels are seeing connect rates drop to 2-5% or lower. That’s a 50-70% decline in the number of actual conversations your team has.

What does this mean operationally?

You need to make 3x as many dials to have the same number of conversations
Your cost per acquisition skyrockets
Sales cycles lengthen because you can’t reach prospects
Your lead lists burn faster with fewer conversions
Agent morale suffers as they spend all day dialing with minimal results

Some sales teams have had to completely restructure their go-to-market strategy because phone outreach became too inefficient. They’ve shifted resources to email, LinkedIn, or other channels—not because those channels are better, but because the phone stopped working.

The Reputation Tax

Even if your calls occasionally get through, operating with poor STIR/SHAKEN compliance creates a “reputation tax” on your business.

Every failed authentication contributes to your overall caller ID reputation. Carriers track which numbers consistently fail authentication checks. Over time, this builds a profile of your numbers as potentially problematic.

Once your reputation is damaged, it becomes a self-reinforcing cycle:

Poor attestation leads to spam labels
Spam labels lead to more blocks and user reports
User reports further damage your reputation
Your reputation causes even properly authenticated calls to get flagged

Breaking out of this cycle requires significant time and effort. You can’t just flip a switch and restore your reputation overnight.

Brand Damage

When prospects finally do answer your calls and see that they came from “Scam Likely,” it immediately undermines trust in your brand.

Think about the psychology: Your prospect has been conditioned to associate spam labels with fraudulent calls. When they answer and realize it’s actually a legitimate business, they wonder:

“Why is this company calling from a spam number?”
“Are they using shady practices?”
“Can I trust them?”

You’re starting every conversation from a position of suspicion rather than neutrality. Your sales reps have to spend the first 30 seconds rebuilding credibility that you wouldn’t have lost if your calls were properly authenticated.

For established brands, this is particularly damaging. You’ve invested years building trust and recognition, only to have it undermined by technical phone system issues that prospects don’t understand.

5 Best Practices to Protect Your Outbound Reputation

The good news is that you’re not helpless. Here are five actionable strategies to improve your STIR/SHAKEN compliance and protect your outbound reputation.

Work With Carriers That Support A-Level Attestation

Not all phone carriers and VoIP providers are created equal when it comes to STIR/SHAKEN support.

If you’re using a budget VoIP service or working through multiple layers of resellers, you’re probably not getting proper authentication. Many smaller providers simply can’t offer A-level attestation because they don’t have direct relationships with the number resources.

Look for providers that:

Explicitly guarantee A-level attestation for business customers
Have direct carrier relationships (not just reselling services)
Support STIR/SHAKEN across their entire network
Provide transparency about attestation levels

Don’t be afraid to ask hard questions before signing up:

“What attestation level will my calls receive?”
“Can you guarantee A-level attestation?”
“What happens if my calls get flagged as spam?”

The cheapest provider isn’t always the best choice. Paying slightly more for a carrier that delivers proper authentication will improve your connect rates enough to justify the cost.

Register Your Business Caller ID Identity

Call authentication works best when carriers can verify your business identity. Take these steps to register your information:

Register with your carrier: Provide business documentation proving you’re a legitimate company authorized to use your phone numbers. This might include:

- - Business licenses
  - Tax ID documentation
  - Proof of number ownership
  - Corporate registration

CNAM registration: Ensure your business name is properly registered in CNAM (Calling Name Delivery) databases so it displays correctly on caller ID.
Branded caller ID programs: Some carriers offer programs where verified businesses can display their logo and business name on modern smartphones. While not directly related to STIR/SHAKEN, this adds another layer of legitimacy.

The more information carriers have about your business, the more confidence they can have in authenticating your calls.

Maintain Responsible Dialing Behavior

Even with perfect A-level attestation, you can still end up flagged if your dialing behavior looks like a spammer.

Responsible practices include:

Reasonable call volumes: Don’t make 1,000 calls per day from a single number
Respect time zones: Only call during permitted hours in the recipient’s location
Honor opt-outs: Immediately stop calling people who ask to be removed
Avoid aggressive redialing: Don’t call the same number 10 times in one day
Maintain accurate contact lists: Remove disconnected numbers and bad data

Think of it this way: STIR/SHAKEN proves you are who you say you are. But responsible dialing behavior proves you’re not acting like a scammer.

Carriers use behavioral analysis alongside authentication data. Even perfectly authenticated calls can get flagged if your calling patterns match those of known spam operations.

Monitor Phone Number Reputation

You can’t fix problems you don’t know about. Implement regular monitoring of your outbound numbers:

Check reputation services: Use tools like Free Caller Registry, RoboKiller Lookup, or similar services to see if your numbers are flagged.

Monitor attestation levels: Work with your carrier to track what attestation level your calls are receiving. If you’re expecting A-level but getting B or C, something needs to be fixed.

Track connect rates: Sudden drops in connect rates often indicate reputation problems. Monitor this metric weekly at minimum.

Review spam reports: Some carriers provide feedback about spam reports on your numbers. Pay attention to this data.

When you spot problems early, you can address them before they become catastrophic. Waiting until your connect rates have already crashed makes recovery much harder.

Use modern VoIP infrastructure

If you’re still using traditional landlines or outdated phone systems, you’re fighting STIR/SHAKEN with one hand tied behind your back.

Modern VoIP platforms built for business calling offer:

Native STIR/SHAKEN support
Proper SIP header handling
Integration with authentication systems
Tools for managing caller ID reputation
Compliance features to avoid behavioral flags

At Call Logic, our platform is built from the ground up to work within the STIR/SHAKEN framework. We handle the technical complexity so you can focus on having conversations with prospects.

Making the switch to modern infrastructure isn’t just about call authentication—it also unlocks features like:

Better call quality
Advanced analytics and reporting
CRM integration
Team management tools
Compliance automation

The upfront investment in proper technology pays for itself through improved connect rates and operational efficiency.

The Bottom Line on STIR/SHAKEN

STIR/SHAKEN isn’t going away. If anything, authentication requirements will get stricter as carriers continue fighting spam calls. The question isn’t whether you need to adapt—it’s how quickly you can do so.

The businesses that thrive in this new environment are those that:

Understand how call authentication actually works
Partner with carriers that support proper attestation
Maintain responsible dialing practices
Monitor and protect their caller ID reputation
Invest in modern infrastructure built for authenticated calling

Yes, STIR/SHAKEN has made outbound sales harder. But it’s also created an opportunity: Sales teams that figure this out will have a significant competitive advantage over those that don’t.

When your competitors are getting 3% connect rates because their calls are flagged as spam, and you’re connecting at 12% because you’ve mastered STIR/SHAKEN compliance, you win. You have more conversations, close more deals, and grow faster.

The key is taking this seriously now rather than waiting until your connect rates force you to act.

At Call Logic, we help sales teams navigate the technical complexities of modern outbound calling. Our platform handles STIR/SHAKEN compliance automatically while giving you the tools to monitor and protect your reputation.

The phone isn’t dead—but the way we use it has changed. Understanding frameworks like STIR/SHAKEN is essential for anyone who depends on outbound calling to drive revenue.

Call Logic’s power dialer is built for the STIR/SHAKEN era. We help you maintain proper authentication, monitor your reputation, and keep your calls connecting. Call for your free consultation today!

STIR SHAKEN Explained: How It Affects Outbound Sales