hung up, no one there

Thank you sooo much. This same thing was happening to my elderly mother after asking them to not call her anymore. She would put stuff out for them and they wouldn't show up. So the phone rang off the hook, like every 10-20 minutes. She'd try calling back and either get a busy or get hung up on. I told her it sounded like a computer call and to block it. It's good to be able to solve the mystery!

It's Community Service for the Blind.  The trucks that come to collect used articles from your home.  We have caller ID and they call constantly.

Revceived call from  206-268-6629.  No one on the other end. Obviously a computer dialed call as call dropped after 30 seconds of dead air.  Retreived call back number and have redialed several times.  Always busy.  Google search says number is owned by Teleport Communications.