Cold calls are being flagged as spam more than ever, and it’s costing businesses revenue. Here’s why:
- Carrier AI systems: Providers like AT&T and Verizon use advanced filters to analyze call patterns. High volume, short duration, and low answer rates mimic robocalls, leading to spam labels.
- STIR/SHAKEN regulations: These verify caller identity but don’t guarantee delivery. Calls with lower attestation levels (B or C) are more likely to be blocked.
- Dialing habits: Practices like repeated calls, poor list hygiene, and using unverified numbers trigger spam filters.
Key Fixes:
- Secure A-level attestation for your numbers.
- Limit call volume per number to 50–70 daily.
- Scrub contact lists to remove invalid or inactive numbers.
- Use a compliance-focused dialer with real-time monitoring.
- Register numbers with analytics platforms like Hiya and TNS.
Improving call behavior and verifying your identity can significantly boost answer rates and reduce spam flags.
Why Your Sales Calls Show Up as SPAM (and What You Can Do To Fix It)
sbb-itb-ee13fa1
Why Cold Calls Get Flagged as Spam
To improve your cold call success rate, it’s crucial to understand what triggers spam filters. These filters are influenced by three main factors: carrier AI systems, federal regulations, and your own dialing practices. Together, these determine whether your call reaches a prospect or gets blocked before it even rings.
How Carrier AI Filters Robocalls
Major carriers like AT&T, Verizon, and T-Mobile rely on machine learning tools from providers like Hiya, TNS/Call Guardian, and First Orion to analyze call behavior. These systems don’t just look at who is calling but also examine how the call is made. Metrics such as call volume, duration, answer rates, and whether your number receives inbound calls all play a role. If your call patterns resemble robocalling – think high volume, short calls, and low answer rates – your number is likely to be flagged, even if you’re operating legitimately.
"The system isn’t judging the business. It’s judging the behavior."
- Vivek Zaveri, Founder and CEO, Meera
On top of carrier systems, mobile operating systems like iOS and Android add another layer of defense. They use on-device machine learning to silence calls from unknown numbers based on user interaction history. This means even legitimate calls could be silenced if they appear unfamiliar. These technical hurdles are compounded by federal regulations, which further shape how calls are handled.
What STIR/SHAKEN Regulations Mean for Sales Teams
STIR/SHAKEN (Secure Telephone Identity Revisited and Signature-based Handling of Asserted Information Using toKENs) is a federal initiative aimed at verifying caller identity and combating number spoofing. It uses digital certificates to confirm that the caller is legitimate.
However, while STIR/SHAKEN ensures identity verification, it doesn’t guarantee call delivery. Even authenticated calls can be blocked if your dialing behavior triggers spam filters. Under FCC safe harbor rules, carriers have significant leeway to block calls they classify as "unwanted" based on behavioral patterns.
"STIR/SHAKEN verifies that you are who you say you are, but it does not determine whether the call is wanted."
- Vivek Zaveri, Founder and CEO, Meera
Calls are categorized by attestation levels – A, B, and C – with lower levels facing stricter scrutiny. Since STIR/SHAKEN’s implementation, robocalls have dropped by about 60% since 2019. However, legitimate business calls often get caught in the system’s crossfire. While identity verification is a step forward, dialing practices remain a critical factor in avoiding spam flags.
What Triggers Spam Flags on Outbound Calls
Certain behaviors are red flags for spam filters. High call volumes – more than 100–150 calls per day – combined with short call durations under 30 seconds suggest low engagement and trigger spam labels. Low connection rates further reinforce these labels, leading machine learning systems to classify even valid calls as unwanted.
Other problematic practices include repeated calls to the same number, high outbound traffic with few inbound responses, and calling disconnected or invalid numbers due to poor data hygiene. Predictive dialers that exceed agent capacity also create "dead air", a behavior often associated with spam. Additionally, frequently swapping flagged numbers for new ones mimics scam tactics, drawing more scrutiny from carriers.
The numbers are telling: about 33% of all outbound calls are flagged as spam monthly, and 25–30% of legitimate business numbers are incorrectly tagged by analytics engines. For sales teams, these misclassifications aren’t just a technical hiccup – they’re a direct hit to revenue that requires immediate action.
STIR/SHAKEN Attestation Levels Explained
STIR/SHAKEN Attestation Levels: A, B, and C Comparison Chart
Understanding what causes spam flags is only half the battle. To tackle these issues effectively, you need to grasp how attestation levels work. These levels – A, B, and C – are assigned by carriers to indicate how thoroughly your identity and phone number usage have been verified.
Currently, 95% of voice traffic among top U.S. Tier-1 carriers uses A-level attestation. Despite this, many sales teams unknowingly operate at lower levels, significantly increasing the risk of their calls being flagged. Proper attestation not only validates your call’s authenticity but also enhances its chances of being delivered in today’s strict telecom environment.
A-Level Attestation: Full Verification
A-level attestation is the highest standard. It confirms that the carrier has fully verified your business identity through Know Your Customer (KYC) protocols and that you are authorized to use the phone number displayed. Achieving this level often requires purchasing numbers directly from your carrier or submitting a signed Letter of Authorization (LOA) for third-party numbers.
Calls with A-level attestation often display a "Verified" checkmark, which can boost answer rates by 77%. While this level of attestation doesn’t completely shield your calls from spam filters – your dialing behavior still plays a role – it establishes the trust necessary to avoid automatic blocking and improves your chances of connecting with prospects.
B-Level and C-Level Attestation Problems
B-Level (Partial Attestation) means that while your identity has been verified, the carrier cannot confirm your authority to use the specific caller ID number. This is common in "Bring Your Own Carrier" (BYOC) setups or when using numbers hosted by a different provider. Without the "Verified" checkmark, B-level calls face greater scrutiny from carrier analytics.
C-Level (Gateway Attestation) represents the lowest trust level. Here, only the call’s entry point is verified, without any confirmation of identity or ownership. These calls are often blocked outright. In fact, some major carriers have policies that automatically reject C-level calls due to their untraceable nature. As Tendril highlights:
"C-attested calls are effectively ‘dead on arrival’ – the call will probably never reach a live person in a useful way".
If your calls are falling under C-level attestation, it’s essential to review your routing setup immediately.
Attestation Level Comparison
| Attestation Level | What’s Verified | Trust Indicator | Deliverability Impact |
|---|---|---|---|
| A (Full) | Identity + Number Ownership | "Verified" checkmark on many devices | Highest; least likely to be flagged or blocked |
| B (Partial) | Identity only; Number NOT verified | No "Verified" indicator | High risk; often triggers spam analytics |
| C (Gateway) | Entry point only (neither verified) | No "Verified" indicator | Guaranteed failure; highly likely to be blocked or labeled "Scam Likely" |
Calls with A-level attestation stand the best chance of reaching their destination, while B and C levels significantly increase the likelihood of spam filtering. Some businesses have reported answer-rate improvements exceeding 500% after upgrading their attestation and reputation signals. For any cold-calling strategy in 2026, securing A-level attestation is not just helpful – it’s essential.
With a clear understanding of attestation levels, let’s dive into 10 actionable steps to prevent your calls from being flagged.
10 Steps to Stop Your Cold Calls From Being Flagged
Now that you know about attestation levels, let’s dive into actionable steps to prevent your cold calls from being flagged. A staggering 81% of businesses report losing revenue because their legitimate calls are mislabeled as spam. These steps cover both technical verifications and behavioral adjustments to help you sidestep carrier AI filters.
The fixes are mostly simple. The goal? Prove your identity through proper attestation and adopt calling habits that feel human. As Vivek Zaveri, CEO of Meera, explains:
"The system isn’t judging the business. It’s judging the behavior."
Step 1: Secure A-Level Attestation for All Numbers
Start by working with your phone service provider to ensure all outbound numbers have A-level attestation. This involves verifying your business identity through Know Your Customer (KYC) protocols and confirming your authorization to use each number. If your numbers are stuck at B- or C-level attestation, consider switching to a provider that offers A-level certification.
Step 2: Buy Numbers Directly From Carriers
Always purchase phone numbers directly from carriers instead of third-party resellers. Why? Numbers from carriers come with proper ownership records, which are vital for achieving A-level attestation. Reseller numbers often lack this documentation, putting you at risk of lower attestation levels and spam flags.
Step 3: Rotate Phone Numbers Strategically
To avoid volume-based spam filters, limit each phone number to 50–70 calls per day. If you’re making over 500 calls daily, use a pool of at least 10 numbers and spread the calls across them. This prevents any single number from displaying robocaller-like behavior. Also, avoid repeatedly calling the same geographic area from one number to steer clear of "neighbor spoofing" patterns.
Step 4: Adjust Your Call Pacing
Maintain natural calling patterns. Calls that consistently last under 30 seconds can raise red flags, so train your team to aim for conversations that last at least 30 seconds, even if the prospect isn’t interested. Also, don’t overload new numbers with high call volumes right away – gradually increase their usage.
Step 5: Scrub Your Lists Regularly
Before launching campaigns, scrub your contact lists against Do-Not-Call (DNC) registries and internal opt-out lists. Violating DNC rules can lead to fines of over $50,120 per illegal call. Additionally, clean your lists to remove inactive or unassigned numbers, as these suggest poor data hygiene.
Step 6: Stick to Legal Calling Hours
Make your calls between 8:00 a.m. and 9:00 p.m. in your prospect’s local time zone. This aligns with the Telephone Consumer Protection Act (TCPA) and reduces the risk of being flagged. Calls outside these hours often resemble robocalls or scams.
Step 7: Leave Professional Voicemails
Leaving a clear voicemail can help prove the call was made by a person. Keep messages short – under 20 seconds – and include your name, company, and reason for calling. Calls that disconnect immediately after reaching voicemail mimic robodialer behavior and could hurt your reputation.
Step 8: Avoid Cheap Routing Providers
Choose carriers that offer A-level attestation and maintain strong ties with analytics platforms like Hiya, TNS, and First Orion. Cheaper providers may route calls through international gateways, resulting in C-level attestation. While the upfront cost of premium providers is higher, the long-term payoff is better answer rates and fewer flagged calls.
Step 9: Use a Compliance-Focused Dialer System
Invest in dialer software with features like automated reputation monitoring, spam flag detection, and compliance tools. A good dialer will scrub DNC lists, enforce legal calling hours, and limit daily call volumes per number. Advanced systems even use AI to spot flagged numbers and rotate them out automatically, preserving your answer rates.
Step 10: Monitor Your Caller ID Reputation
Register your business numbers with the Free Caller Registry to ensure your verified company name appears on recipients’ screens. Platforms like Hiya (AT&T), TNS (Verizon), and First Orion (T-Mobile) use this information to identify legitimate businesses. Regularly check your numbers’ reputations using tools like Hiya or Nomorobo. Since 25% to 30% of legitimate business numbers are misclassified as spam, proactive monitoring lets you dispute false flags quickly. If a number gets flagged, stop using it immediately and file a dispute with the relevant analytics provider.
How to Choose a Compliant Dialer
Your dialer plays a key role in ensuring your calls get answered. The wrong choice can seriously hurt your answer rates, even if you do everything else right. Here’s a fact to consider: over 95% of calls marked as "Spam Likely" go unanswered. That’s why picking a dialer that actively avoids spam flags is essential for your success.
The right dialer doesn’t just make calls – it protects your reputation with carriers and analytics platforms. To make an informed choice, focus on three key areas: technical features, red flags to avoid, and compliance documentation.
Required Dialer Features
To stay ahead, your dialer needs to meet several criteria:
- A-Level attestation for every call: This confirms your business identity and your right to use specific phone numbers. Be cautious with BYOC (Bring Your Own Carrier) models, as they may not integrate deeply enough to maintain high attestation levels.
- Automatic registration with analytics platforms: Your numbers should be pre-registered with Hiya (AT&T), TNS (Verizon), First Orion (T-Mobile), and the Free Caller Registry. This establishes "Trusted Caller" status before you even make your first call.
- Real-time reputation monitoring: Advanced systems use AI to constantly check number health and flag potential "Spam Likely" issues. If a number gets flagged, the system should replace it automatically to maintain answer rates.
- Integrated DNC scrubbing: The dialer should cross-check both National and internal Do Not Call lists and verify numbers against the Reassigned Numbers Database. Non-compliance can lead to fines of over $50,120 per call.
- Dynamic pacing controls: To avoid robocall patterns, the system should evenly distribute call volume across verified numbers and prevent sudden spikes. It should also enforce legal calling hours based on the prospect’s time zone.
- CRM-level audit trails: Look for systems that log detailed call data – dates, times, results, and consent sources – directly into your CRM (like Salesforce). This creates a clear record for audits or legal inquiries.
These features work together to protect your reputation and ensure your calls reach their intended audience.
Warning Signs to Avoid
Not all dialers are created equal. Be wary of these red flags:
- "Unlimited" numbers without registration: These often rely on cheap routing methods, leading to lower attestation levels (C-Level). As SalesHive points out:
"If you can’t prove who you are, why you’re calling, and that you’ll stop when asked, you don’t have a calling program – you have a liability."
- Lack of CRM integration or proof of consent: If the system doesn’t sync with your CRM or track consent for every call, it’s a risk.
- No automatic DNC scrubbing: Dialers that don’t enforce abandonment rate limits (below 3%) or skip DNC checks are a compliance nightmare.
- Neighbor spoofing features: Mimicking the recipient’s area code and prefix is a known fraud tactic and often blocked by carriers.
- Short call durations: High volumes of calls under 10 seconds are a major red flag for spam labeling. Aim for systems that maintain an average call duration above 30 seconds.
How to Check Compliance Documentation
To confirm a provider’s compliance, dig into their documentation:
- Request sample SIP headers: These show how carriers view your calls and confirm A-Level attestation. A provider unwilling to share this is a red flag.
- EIN requirement: Legitimate providers will ask for your Employer Identification Number to complete SHAKEN/STIR and CNAM registration. This step ensures verified business calling.
- Trusted Calling registration: Providers should submit your business details to major analytics platforms (Hiya, TNS, First Orion). Branded caller ID, which displays your verified business name, can boost answer rates by up to 56%.
- Carrier partnerships: Look for providers with direct relationships with major carriers and platforms. They should be able to explain how they maintain A-Level attestation across networks.
- State-specific compliance tools: Some states, like Florida, Oklahoma, and Texas, have stricter telemarketing laws than federal TCPA standards. Your dialer should automatically enforce these rules without extra setup.
At Leads at Scale, our US-based Business Development Representatives rely on dialers that meet all these standards. We handle the technical details – like STIR/SHAKEN compliance, carrier registration, and reputation monitoring – so your team can focus on building connections, not battling spam labels.
How to Track Call Deliverability Improvements
Once you’ve implemented the 10-step checklist, the next step is to ensure your hard work is paying off. The key? Focus on three essential metrics: answer rates, attestation levels, and call completion rates. These will give you a clear picture of whether your deliverability efforts are making a difference.
Track Your Answer Rates
Answer rates are one of the most straightforward indicators of deliverability. When your phone numbers are clean and trusted, you should see answer rates of 5–15% for cold calls. If your rates drop below 5%, it could mean your number has been flagged. Brad Morgan, CTO of Healthcare Solutions Group, highlights the importance of even small improvements:
"Even a one-percent increase in contact rate can translate into millions of dollars for large outbound operations."
To get the most accurate insights, track answer rates at the individual phone number level, not just across your entire team. For example, if one number’s answer rate falls from 12% to 4%, it might be flagged – even if your team’s overall performance looks fine. Review these stats weekly and break them down by number pools (like SDR outbound or customer follow-up) to spot problems early.
Verify Your Attestation Levels
Attestation levels reflect how much carriers trust your calls. An A-Level attestation means your number is fully verified, showing that you own and are authorized to use it. On the other hand, B-Level and C-Level attestations are more likely to trigger spam filters.
To check your attestation status, look at recent SIP headers, which display your current level. You can also use tools like AT&T Call Protection, T-Mobile Scam Shield, or Verizon Call Filter to see how your numbers appear to recipients.
Monitor Call Completion Rates
Once your numbers are verified, it’s time to keep an eye on call performance. Call completion rates help you identify whether carriers are dropping your calls before they connect. Watch for two red flags: a high number of calls lasting less than 10–15 seconds and unexpected drops in connection rates, even if your dialing volume stays steady.
To avoid triggering automated blocks, aim for an average call duration of over 30 seconds. Shorter calls can create "micro-call" patterns that carriers may flag. Additionally, keep an eye on complaint rates (e.g., complaints per 1,000 calls), as these can signal reputation issues that could hurt your answer rates. Metrics like these directly link back to the technical adjustments you’ve made – such as achieving proper attestation levels and maintaining controlled call pacing.
Key Metrics to Watch
Here’s a quick snapshot of what to look for:
| Metric | Healthy Signal | Problem Signal |
|---|---|---|
| Answer Rate | 5–15% | Below 5% or a sudden 20–50% drop |
| Attestation Level | A-Level (Full Verification) | B-Level or C-Level |
| Average Call Duration | Above 30 seconds | High volume of calls under 10 seconds |
| Call Volume Pattern | Steady, predictable pacing | Sudden spikes or rapid-fire redials |
Integrate these metrics into the same dashboard where you track meetings booked and pipeline progress. Remember, deliverability isn’t just about tech fixes – it’s about ensuring your team can consistently connect with prospects.
FAQs
How can I tell if my number is “Spam Likely” before I lose meetings?
Carriers rely on AI to identify spam-like behavior, flagging numbers with patterns such as high call volumes or low answer rates. This could result in your caller ID appearing as "Spam Likely" on recipients’ devices. To check if your number is flagged, you can use tools designed to test how your caller ID displays.
To avoid being flagged, stick to these best practices: rotate your numbers regularly, maintain proper pacing for your calls, and ensure your caller ID complies with carrier standards. These steps can help keep your number in good standing and improve your call connection rates.
What’s the fastest way to move from B/C attestation to A-level attestation?
To move from B/C-level to A-level attestation quickly, make sure your caller ID aligns with carrier verification standards and adhere to strict compliance practices. Pay close attention to caller ID verification, appropriate number rotation, and call pacing. By following carrier protocols consistently and maintaining compliant calling practices, you can build trust with carriers and achieve A-level attestation more efficiently.
Should I switch from a predictive dialer to power/preview dialing to improve deliverability?
Yes, switching to power dialing or preview dialing can help improve call deliverability. Unlike predictive dialers – which often trigger spam flags by dialing multiple numbers at once and creating patterns carriers identify as robotic – these methods use a more controlled approach. This controlled pacing reduces the risk of being flagged as spam and aligns more effectively with STIR/SHAKEN regulations. By making this shift, you can improve your call reputation and achieve better deliverability rates.
