Possible spam or fraud. Didn’t know the number. Let it ring to see if they would leave a voicemail. No voicemail never left. Called back immediately and it already stated that the number was “a vacant numberâ€. Get numerous of these a day from different numbers. I would think it’s safe to **sume it’s a robocall/ fraudulent/etc- given that if they just called the number was activated. So how in less then a minute does it become vacant. Since I have IPhone. I have silenced all calls that are not programmed and installed Apples new APP after the update. I know a lot of people with IPhones that still do not know that they can go into their settings and silence all calls that are not in your contacts. If it’s a legit person, company, etc. they are still able to leave a voicemail and can still text you. If you block a call with IPhone they can only leave a voicemail that goes to a folder “blocked voicemailsâ€. However if they text you and they are blocked you will not receive like Androids are able to do.