Back in times when my DD did not have a phone we used to have check points in case we got separated, check points changed as we were walking, for example fountain at Epcot, then as we went to world showcase, it was infront of Mexica and so on.
We had dog tags on DD last trip but we got some new cell phone numbers so I had to reorder a new dog tag last night. You can get them for around $2.99 engraved off ebay. I think I payed around $4.50 shipped to me.
I bought those name ID tags from a machine in Walmart. I heard this advice on the boards. My kids loved wearing them. They even had a Tink tag. On the back, I just put "Mom's cell phone # --- --- ----" If they got separated from us they had to show a cast member their tag and then someone could call to find me.