STIR/SHAKEN Explained in Under 3 Minutes: Why Your Business Calls Are Showing Up as "Spam Likely"

You’ve spent weeks refining your sales script, training your team, and investing in the latest cloud telephony stack. You dial a high-value prospect, expecting a professional introduction, only to be met with a cold, immediate hang-up. Or worse, the call goes straight to voicemail without a single ring.

The culprit isn't your product or your pitch: it’s the "Spam Likely" label flashing on your customer's smartphone screen.

In the modern world of business communication, your phone number is your digital identity. If that identity is compromised by the FCC’s STIR/SHAKEN framework, your outbound reach is effectively dead on arrival. Understanding how this system works isn't just for IT departments anymore; it’s a prerequisite for any business that relies on the phone to drive revenue.

What is STIR/SHAKEN? (The 3-Minute Breakdown)

At its core, STIR/SHAKEN is a pair of protocols designed to restore trust in the telephone ecosystem. Before these rules were enforced, the "From" field on a phone call was as easy to fake as a return address on a physical envelope. Scammers used this loophole to "spoof" numbers: making a call from overseas look like it was coming from a local area code or a trusted government agency.

STIR/SHAKEN stands for:

• STIR: Secure Telephone Identity Revisited

• SHAKEN: Signature-based Handling of Asserted information using toKENs

Think of it as a digital passport for every phone call. When you place a call, your service provider "signs" the call with a digital certificate. This certificate travels with the call through the network. When the call reaches the recipient's carrier, they check the certificate. If the signature is valid, the call is delivered normally. If it’s missing or suspicious, the carrier flags it as "Spam Likely" or blocks it entirely.

The Three Levels of Trust: Why Attestation Matters

Not all digital signatures are created equal. The STIR/SHAKEN framework uses three levels of "attestation" to tell the receiving carrier how much they should trust the caller. If your business calls are getting flagged, it’s almost certainly because you aren't hitting the "Grade A" mark.

1. Full Attestation (Level A)

This is the gold standard. Level A means the service provider knows exactly who the customer is and can confirm that the customer has the legal right to use the phone number being displayed. When you have Level A attestation, your calls are highly unlikely to be flagged as spam.

2. Partial Attestation (Level B)

This occurs when the service provider knows who the customer is (the call originated on their network), but they cannot verify that the customer is authorized to use that specific number. This often happens in complex business communication setups where numbers are hosted by one provider but the dialer is hosted by another.

3. Gateway Attestation (Level C)

This is the "red flag" zone. Level C means the provider only knows where they received the call from (a gateway), but they have no information about the original caller or their right to use the number. Calls with Level C attestation are the most frequent victims of "Spam Likely" labels.

Why Your Business Calls are Failing the Test

You might be a legitimate business with a physical office and a clean record, but your calls can still be labeled as spam. Here are the most common reasons why this happens in the world of cloud telephony:

• Routing Through "Least Cost" Carriers: Some budget-friendly providers route your calls through multiple intermediate carriers to save pennies. Every time your call hops to a new carrier, the digital signature risks being stripped away or downgraded to Level C.

• Unregistered Numbers: If you haven't properly registered your business identity with your carrier, they cannot grant you Level A attestation. You are essentially an "unverified user" in their system.

• High Call Volume Patterns: Even with a good signature, if you are making thousands of short-duration calls, carrier algorithms might flag your behavior as spammy, regardless of your STIR/SHAKEN status.

• International Gateways: Calls originating outside of the United States often lose their attestation when they cross the border, leading to a "Spam Likely" tag for your international sales teams.

If you find yourself struggling with these issues, you might be making one of the 7 common cloud telephony mistakes that cost businesses thousands in lost opportunities.

The ROI of "Clean" Calls

The impact of STIR/SHAKEN isn't just a technical annoyance; it’s a direct hit to your bottom line. When your calls are flagged:

1. Answer rates plummet: Most consumers (and B2B buyers) will not answer a call labeled "Spam Likely."

2. Brand reputation suffers: Seeing your company name associated with a spam warning creates a "guilty by association" feeling in the prospect's mind.

3. Wasted Labor: Your sales and support teams spend hours dialing into a void, significantly increasing your cost-per-acquisition.

For businesses looking to maximize their cloud telephony ROI, ensuring Level A attestation is the single most effective "quick fix" available.

How to Fix Your "Spam Likely" Problem

Fixing your reputation in the eyes of carriers requires a proactive approach. You cannot simply wait for the problem to go away; the algorithms are only getting stricter.

Step 1: Audit Your Current Provider

Ask your cloud telephony provider point-blank: "What attestation level are you giving my outbound calls?" If they can't give you a straight answer or if they admit to Level B or C, it’s time to re-evaluate your partnership. High-tier solutions like Genesys Cloud offer robust tools to manage your call identity effectively.

Step 2: Register Your Brand (KYC)

"Know Your Customer" (KYC) isn't just for banks anymore. You need to provide your carrier with your tax ID, physical address, and a list of all numbers you own. This allows them to vouch for you in the STIR/SHAKEN ecosystem.

Step 3: Implement Branded Caller ID

Beyond just avoiding "Spam Likely," you can actually display your company name and logo on many mobile devices. This is the "VIP Pass" of business communication. It bypasses suspicion and immediately builds trust before the prospect even picks up the phone.

Step 4: Monitor Your Reputation

Check your numbers regularly. There are several tools available that allow you to see how your numbers are being categorized across major carriers like Verizon, AT&T, and T-Mobile. If a number gets "burned" (flagged), pull it out of your rotation and investigate the cause.

The Future of Trust in Business Communication

As we move further into 2026, the intersection of AI and telephony is creating new challenges. While agentic AI can revolutionize how you handle customer interactions, it also increases the volume of automated calls, making STIR/SHAKEN compliance even more critical.

Carriers are now using AI to analyze call patterns in real-time. If your business doesn't have a solid "digital identity" strategy, even your most legitimate AI-driven outreach will be silenced by carrier filters.

Final Actionable Takeaways

• Don't Settle for "C": Demand Level A attestation from your provider. If they can't provide it, they are effectively sabotaging your outreach.

• Centralize Your Numbers: Avoid using a patchwork of different providers for different departments. This often leads to "Partial Attestation" (Level B) because the provider can't verify ownership of the numbers.

• Stay Informed: The rules around STIR/SHAKEN and FCC compliance evolve. Check our sitemap for the latest updates on telephony regulations.

If you're unsure where your business stands, or if your current migration to the cloud feels stalled by technical hurdles, don't navigate it alone. Exploring a 5-step framework for migration can help you avoid the pitfalls that lead to "Spam Likely" labels.

At Dunamis Consulting Inc, we specialize in ensuring your cloud telephony infrastructure is built for trust, clarity, and performance. Don't let a "Spam Likely" tag be the reason your next big deal falls through.

Ready to clean up your caller ID? Contact Dunamis Consulting today for a full audit of your telephony environment.