This mama did what and self-preserving soul would, and hauled out two plastic cups, a skewer, and ten feet of kitchen string. Voila! We have a telephone system.
It killed me how easy this was: I just poked one hole in the bottom of each cup with the skewer, threaded the kitchen string through and knotted it on the inside of the cups. You’ll want to pull (very) taught and have one person listen while the other speaks. I promise you and your kid will be amazed at how incredibly well this works.
Bjørn and I spent a good bit of time telling each other silly secrets that Dad couldn’t hear :-)