@tbsvttr
It sounds like you've already taken some thorough steps to troubleshoot the issue with the phone number 37ce8038-7d4c-4fcb-a4d7-580bf07b6bd0. Since the problem persists despite your efforts, and the calls to the number are not appearing in the logs, it seems there might be a deeper issue that requires further investigation.
Given that the message being played is not set by you and the number's behavior is not consistent with your other numbers, I would recommend reaching out to Vonage support for a more detailed look into the number's configuration on their end. They should be able to check if there are any settings or configurations that are causing this message to be played, especially since it started after attempting to use the number for an outbound call via API.
Please contact Vonage support for more info on this, as they will have the necessary tools and access to diagnose and resolve the issue with the specific number in question.