I am not able to replicate that behavior in our organization, so I am wondering if it is a carrier issue...though, if you hear ringback, then the call progress should be getting through to PureCloud properly.
If I place an outbound call and let the phone ring a few times, then hang up before it connects to voicemail, I still see the call in my Call History on the user.
I don't have access on that particular org to see the Interactions, so I don't know for sure it shows up there.