I'm looking for the name of a black and white 1950s science fiction movie... it starts out with a man who finds a small black box with a little cone on one side at a construction site dig. A little boy, I think his son, asks to keep the box. He takes this box home and somehow drops it and it shatters into pieces. He goes to sleep with a piece of the object in his hand and next thing we know he teleports to a different world. He convinces someone in his family about this experience and takes them to this other world and they find many of these black boxes. They find a dead humanoid with headgear that has a wire connected to one of these boxes. They put the head gear on and find out information that is contained in the box. The information they learn is about 2 different planets which are at war.
They then are able to teleport from planet to planet when they stand on a round platform. I thought it was called the Terminots or something like that.