No clue who this is but they keep calling and leave messages for me to call back.  No company name.

It's Kaiser Permanente, an HMO.  It's an automated "customer help" line.

tried calling the number, it rang twice, then dial tone...

I called Kaiser tech support about this and they can't identify this # as their own, even though the automated voice from this call says "I'm calling from Kaiser."

Kaiser Tech support recommends, not calling the number back.

Have no clue who this is.  They leave a auto voicemail for me to call them back but they don't leave any further info.