Spam Mislabeling for Voice API – Sinch

Calling Name showing as SPAM? Here's what you can do

You’re trying to reach your customers, and instead your calls are getting ignored or blocked because they are being labeled as Spam Likely, Scam Risk, Robo or similar..… you’re not alone.

This is a very common industry-wide issue and we’re on your side in helping you work through it.

Why This Happens

Call labeling is handled by carriers (like AT&T, Verizon, T-Mobile) and Third-party analytics companies (like TNS, Hiya, First Orion, Neustar).

These systems are designed to stop spam and fraud, however sometimes legitimate businesses can get caught in the mix and end up getting mislabeled.

When the analytics companies determine if calls are related to spam, they look at the following:

How your numbers are being used
Calling patterns and volume
Customer complaints or blocking activity
Historical reputation of the number
Calling Name (CNAM).

What It Looks Like

Different carriers and analytics providers label calls differently.

Call Label	Carrier / Provider
Fraudulent Call	Altice, Fidelity Communications, Telzio, Windstream
Spam Risk, Fraud Risk	AT&T
Blocked – High Spam Risk	Comcast (Xfinity)
Potential Spam	C-Spire, US Cellular, Verizon
Robo Caller	Frontier, Lumen
Spam Likely	Spectrum (Charter)
Scam Likely	T-Mobile
Spam	Truecaller
Robo? Or Spam? (Prepend)	Altice, Comcast (Xfinity), Fidelity Communications, Windstream

How You Can Fix It

There isn’t a single instant fix, but the following steps will give you the best chance of improving the issue overall.

1. Configure Calling Name Value (CNAM)

Make sure your Calling Name is set with an accurate name customers will recognize.
Missing, generic, or incorrect CNAM can negatively impact how your calls are scored, making them more likely to be labeled as spam.

2. Register your numbers (most important step)

Use the Free Caller Registry website to register your numbers. This site will register your numbers with the major analytics providers (e.g. First Orion, Hiya, TNS) that support multiple phone providers to help establish that your calls are legitimate.

Analytics Company	Carrier / Provider	Registration Link
Free Caller Registry	Multiple	http://www.freecallerregistry.com/
First Orion	Tmobile	https://firstorion.com/register/
HIYA	ATT	https://hiyahelp.zendesk.com/hc/en-us/requests/new
TNS	Verizon	https://tnsi.com/robocall-mitigation/
Neustar	Multiple	http://www.home.neustar/support

Note - After registering, analytics systems will still evaluate your traffic based on behavior.

3. Follow Calling Best Practices

Call labeling is influenced by how calls are placed and how recipients interact with them.
For a full list of recommended calling practices, see Calling Best Practices section below.

What If the Issue Persists?

If your calls are still being labeled as spam after updating CNAM and registering with the Free Caller Registry, the next step is to submit your number(s) directly to the provider responsible for labeling on the affected carrier’s network. Each provider has its own process and review timeline.

Note - If you are unsure which provider applies to a specific number, Sinch Support may be able to assist in identifying the correct carrier.

Provider and Carrier Labels
Carrier / Provider	Labeling
Altice	Fraudulent Call or CNAM prepend of Spam? or Robo?
ATT	Spam Risk or Fraud Risk
Comcast (Xfinity)	Blocked – High Spam Risk or CNAM prepend of Spam?
C-Spire	Potential Spam
Fidelity	Fraudulent Call or CNAM prepend of Spam?
Frontier	Robocaller
Lumen	Robocaller
Spectrum (Charter)	Spam Likely
Telzio	Fraudulent Call
T-Mobile	Scam Likely
Truecaller	Spam
US Cellular	Potential Spam
Verizon	Potential Spam
Windstream	Fraudulent Call or CNAM prepend of Spam?
Sinch	Potential Risk

What if the Issue Persists After Working with Provider?

If you’ve engaged the problem provider and you’re still stuck, bring it to us.

We can help with the following:

Help you understand what might be triggering the labeling
Guide you through next steps
Assist where escalation is possible

At the same time, we want to be transparent:

Carriers and analytics companies control the labeling systems
They’ve intentionally pushed registration and reputation management to end users
That means we don’t have a direct remove spam label button

But that doesn’t mean you’re on your own. We’ll work through it with you.

Calling Best Practices

Build Trust with Consistent, Legitimate Traffic

Maintain consistent, natural calling patterns
Avoid sudden spikes in volume or very short duration calls at scale. Predictable usage builds trust over time.
Ensure strong customer validation (KYC)
Confirm that traffic on your account is legitimate. This helps protect overall number reputation.

What Can Accidentally Make It Worse

The first few calls from a number are more likely to be labeled due to no reputation
Testing new numbers repeatedly
- This is one of the most common issues. While it feels logical to test a new number:
Numbers with very low call volume are often flagged as suspicious
Cycling through numbers reinforces this pattern
This can create a loop where every new number continues to be flagged.

Day-to-Day Calling Practices

Avoid high-volume call bursts
Spread outbound calls over time to avoid looking like automated traffic.
Limit repeat calls to the same number
Frequent attempts in a short window can increase spam risk.
Keep calling patterns consistent
Sudden changes in volume, timing, or location can trigger filtering.
Use consistent outbound numbers
Frequently rotating numbers can reduce trust and reputation.
Watch answer rates and rejections
Low answer rates or frequent declines can impact how calls are labeled.

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