Troubleshooting Calls Marked as Spam or Blocked by Destination Carriers

Overview

This article explains how to troubleshoot and resolve issues where outbound calls from Evo Voice numbers are being marked as “Spam” or are rejected by the recipient’s carrier (e.g., AT&T, Verizon, T-Mobile). This issue typically arises due to spam labeling or call blocking systems managed by the recipient’s carrier or their analytics partners.

Symptoms

Outbound calls display as “Scam Likely” or “Spam Risk” on the recipient’s phone.
Calls are not connecting or are being immediately rejected.
The Evo Voice app shows a SIP Status 603 (“Declined”) response from the destination carrier.

Root Cause

Major U.S. carriers such as T-Mobile and Verizon use analytics systems to detect potential spam or fraudulent call patterns.

Legitimate business calls may be incorrectly marked as spam due to:

High outbound call volume patterns
Recent number assignment
Mismatch or missing CNAM (Caller Name) data
Inconsistent call routing or caller ID configuration

This filtering is controlled by the recipient’s carrier or their analytics partner, not by Evo Voice or Twilio.

Resolution Steps

Step 1: Register Your Toll-Free Numbers

Register your toll-free numbers with carrier analytics registries to verify legitimacy and reduce the likelihood of spam tagging.

For example:

T-Mobile: https://callreporting.t-mobile.com/
First Orion (T-Mobile’s analytics provider): https://portal.firstorion.com
Verizon: https://www.voicespamfeedback.com/vsf
Free Caller Registry: https://freecallerregistry.com/fcr

These registries work with major U.S. carriers to verify numbers and improve call delivery accuracy.

Step 2: Update or Add CNAM (Caller Name)

Ensure your Caller Name (CNAM) is properly registered for all outbound numbers.

This helps display accurate information to recipients and may improve answer rates.

You can request CNAM updates through Evo Voice Support or by completing the CNAM registration form provided by the support team.

Step 3: Validate Call Configuration

Confirm that each number is assigned correctly under the intended company or user profile in Evo Voice.
Check Endpoints → Numbers to ensure routing is configured properly.
Review outbound caller ID settings in Flows → Outbound Rules to confirm that the correct number is being used.

Step 4: Test Calls

After updates, perform a few test calls to multiple carriers (AT&T, Verizon, T-Mobile).

Monitor if the “Spam” or “Scam Likely” label is removed within 24–48 hours after registration and CNAM updates.

Additional Notes

Spam labeling removal is not instant. It may take several days for carrier databases to update.
Evo Voice and Twilio cannot directly control or override carrier spam filters.
Ensure your business maintains consistent, legitimate call behavior to avoid future false positives.