Intermittent inbound call ringing once before going to voicemail

I have a customer who is on a ElastixPBX platform (Asterisk Version 11.25.0) who is reporting that some inbound calls (intermittent) reporting that there are calls coming in that just ring once and then end. The inbound number is not tied to a hunt group. Just wondering if you all ave run into this before?

Welcome to the forum!

This is likely something that would be revealed with a call trace, which you can share via pastebin Providing Great Debug - Support Services - Documentation

Hopefully you’re aware that Elastix was abandoned yard ago, you definitely need a plan to move to a supportable system. Exploit maybe? - #9 by lgaetz