Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

​ To learn more, see the sources I considered: [[1] Debug outbound connection issues](https://docs.retellai.com/reliability/debug-outbound-call) [[2] Debug call disconnection](https://docs.retellai.com/reliability/debug-call-disconnect) ​

### Answer --- This sounds like a short ring followed by disconnection. Check your call history for the disconnection reason and SIP error code in the detailed log—this will help identify the root cause. [(1) ]() Possible causes: -

dial_no_answer

– The number dialed did not answer (call may have been cut short before pickup) . [(1) ]() [(2) ]() -

dial_failed

– Dialing failed with no or unknown SIP error code. -

marked_as_spam

– If your number has high outbound volume without warmup or low pickup rates, it may be flagged by carriers and blocked. [(1) ]() Troubleshooting steps: 1. Check the call's detailed log in your dashboard for the exact disconnection reason and SIP error code. 2. If using custom telephony (e.g., Twilio) , verify your SIP trunk configuration and check with your provider for errors on their side. 3. If using a Retell-purchased number, confirm the destination number can accept calls (currently, Retell numbers can only call US numbers) . 4. If your number is being marked as spam, consider purchasing a new number and warming it up gradually, or register it with the [verified phone number](/build/telephony/verified-phone) feature. Can you share the disconnection reason shown in your call history? That will help narrow down the issue.