Outbound calling is critical for sales and support teams, but nothing undermines performance faster than having your numbers flagged as Spam Likely or blocked by carriers. This guide explains how to prevent your numbers from getting burned, how to check their reputation, and how to improve or remediate reputation issues when they arise.
1. Understanding Number Reputation
Carriers and call analytics providers (Hiya, TNS, First Orion, etc.) use algorithms to score phone numbers. These scores determine whether calls display as Spam Likely, Scam Risk, or are outright blocked.
Factors that influence reputation:
Call patterns: high volume, many short-duration calls, or excessive redials to the same lead.
Answer rates: unanswered calls and quick hang-ups lower reputation.
Complaint rates: recipients manually marking calls as spam.
Number type: VOIP and toll-free numbers are more likely to be flagged.
Shared ranges: if other numbers in the same block are abused, your number may be guilty by association.
2. How to Prevent Your Number from Getting Burned
The best strategy is proactive reputation management. Follow these practices:
Register Properly
The Campaign Registry (TCR): Ensure your brand and campaign are approved through Twilio Trust Hub - we do this for you!
CNAM: Register a Caller ID Name for landline networks through a third-party CNAM provider. You should register your number in the national caller ID database so that your number is no longer marked as a spam caller. This will resolve the error message you hear and display the correct caller ID for your number (note that it will take at least two weeks after registering for this change to take effect).
Branded Caller ID: For wireless carriers, enroll in programs like Verizon Call Filter, AT&T FirstNet, and T-Mobile Scam Shield.
Stir/Shaken Registration: If you have corrected the caller ID and you are still experiencing the error, you may need a Shaken/Stir registration. STIR/SHAKEN digitally validates the handoff of phone calls passing through the complex web of networks, allowing the phone company of the consumer receiving the call to verify that a call is in fact from the number displayed on the Caller ID.
To get this registration done, please reach out to the Support Team via chat or email so that they can get the registration done for you.
Maintain Traffic Hygiene
Warm up new numbers: Start with a small call volume (e.g., <50 calls/day) and scale gradually.
Diversify outbound traffic: Rotate calls across multiple numbers instead of overloading one.
Avoid redials: Do not call the same lead multiple times in a short window.
Keep answer rates healthy: Focus on high-quality lists and good lead data.
Respect call times: Avoid calling too early or late, which triggers complaints.
Monitor Usage Metrics
Track average call duration, answer rate, and call volume per number.
Identify “problem numbers” early before they get flagged.
3. How to Check Your Number’s Reputation
There are several ways to determine whether your numbers are at risk:
Reputation Lookup Tools
Caller ID Reputation – multi-carrier checks and dashboards.
Numeracle – monitoring and remediation services.
Neustar / TransNexus – STIR/SHAKEN and reputation analytics.
Free/Direct Methods
Place test calls to devices on AT&T, Verizon, and T-Mobile networks.
Use apps like Truecaller or Nomorobo to see if your number appears as spam.
Some APIs (e.g., Twilio Fraud Check, third-party fraud APIs) provide risk scores.
What to Look For
Scores above 600 → number is “high risk” and likely flagged.
Carrier labeling (Spam Likely, Scam Risk) → indicates reputation issues.
Dropped calls → number may be blocked outright.
4. How to Improve or Remediate Reputation
If a number is already flagged, you have two options: remediate or retire and replace.
Step 1: Audit Call Behavior
Reduce call volume on the flagged number.
Fix short calls, excessive retries, or patterns that look robotic.
Align caller ID with your registered brand and campaign.
Step 2: File Remediation Requests
Most major analytics companies allow disputes:
Hiya: Submit request
TNS: Report form
First Orion: Call Transparency
What to include:
The flagged number(s).
Your company and use case (legitimate, not robocalls).
Proof of TCR registration.
Example call flows and consent procedures.
Step 3: Replace If Necessary
If a number has a severely poor score (e.g., 800+), remediation may fail. In that case:
Retire the number.
Provision a new number through Twilio or your provider.
Warm it up gradually with careful traffic hygiene.
Step 4: Implement Continuous Monitoring
Subscribe to a monitoring service (Caller ID Reputation, Numeracle).
Run weekly test calls across carriers.
Keep a central log of each number’s reputation status.
5. Best Practices for Long-Term Success
Quality over quantity: Fewer, well-targeted calls lead to better answer rates and protect reputation.
Educate agents: Train staff to avoid rapid hang-ups and to leave meaningful voicemails.
Multiple numbers strategy: Maintain a pool of registered numbers and rotate them strategically.
Transparency: Display your brand name wherever possible through branded caller ID programs.
Key Takeaways
Burned numbers can tank outbound results, but proactive management prevents issues.
Reputation is influenced by call behavior, registration status, and carrier analytics.
Use monitoring tools, test calls, and APIs to track reputation.
Remediation is possible, but some numbers must be retired and replaced.
Long-term success comes from ongoing monitoring, disciplined dialing, and brand transparency.