This is Enterprise Recovery System.  They call me, no one says and thing and then they hang up.  Very nerve-wrecking. I have not Idea what they want and frankly not interested.

This bunch has been calling me since 2011... since they keep trying but never leave a msg, never speak when we pick up, etc... I believe it's the Callback Scam.
They want to plant a virus in your cellphone, which cannot happen via voicemail. What they need is for YOU to connect. If you pick up, or call 'em back, then the virus is planted in a split second. Then they get every shred of info out of your celly.
If they call your landline it's only because they don't know it's a landline.