Getting a "Carrier Rejected" status when making calls can be frustrating, but it’s a common issue in the world of outbound dialing with your AI builder or CRM. Understanding what this means—and what you can do about it—can save you a lot of time and keep your call success rates high.
"Carrier Rejected" almost always points to a telephony-side problem, not an issue with your AI builder.
Warm up new numbers slowly with low call volumes.
Keep platform credentials updated.
Use real, verified numbers from major carriers for best deliverability.
A "Carrier Rejected" message means the call was blocked or not completed by the contact’s service provider, not by your platform. Most often, this happens due to poor number reputation—your number might be flagged as spam or simply not trusted by carriers. The more often this happens, the worse your number’s reputation can get. Codes like 608 and 603 (often visible in Twilio, Telnyx, and other logs) point directly to this problem.
Tip: Carrier rejection can become a compounding issue—the more it happens, the more likely future calls from that number are to be blocked.
Register your numbers with Free Caller Registry. It’s free, and helps carriers recognize your business as legitimate. Take advantage of all verification services offered.
If possible, use SIP trunking instead of just platform numbers. This gives you more control over business profiles, caller IDs, and regulatory features like SHAKEN/STIR. Owning your numbers through SIP also makes swapping numbers easier if you run into issues.
Rotate your numbers using a number pool. This spreads your call volume across several numbers, reducing the risk that any single number gets flagged as spam.
Warm up your numbers slowly, just as you would with a new email sender. Start with low call volumes to your most engaged contacts and ramp up gradually. Focus on getting positive call metrics (like answered calls and good sentiment) before scaling up.
Telephony Status: Check your HIYA spam rating. “Uncertain” is actually good—this means there’s no history of spam for your number.
Verification: Are you registered at Free Caller Registry? If not, do this now.
Caller ID: Check what your contacts actually see when you call.
If you’re using imported numbers and calls are being rejected, first test both inbound and outbound calls. If inbound works but outbound fails, your SIP trunk is likely misconfigured.
For high-volume calling, check your calls-per-second (CPS) rate with your provider. Increase the limit if needed.
Make sure your SIP termination settings and credentials are accurate.
If your number is new or being marked as spam, try using a different one. Always warm up new numbers first.
With platform numbers, check OAuth credentials—expired OAuth can cause failures. Also, remember platform numbers often support US-only calling; for international calls, use imported numbers.
If you see consistent issues, consider using a number from a major carrier like Verizon or RingCentral, register it, and use it for SIP trunking.
Pro Tip: Regularly check your number's spam status with free analytics tools and always keep your credentials and permissions up to date.
