My son is also 4 1/2, and being a single mom, we are often alone as well. We do not have a landline. I have a touch screen cell phone, which makes calling easy for my son. It basically has a picture speed dial. My son learned quite quickly how to get to the speed dial menu, touch the person he's trying to call's photo, and touch the dial button. Without this, I don't think he'd be able to dial out just yet. We've started teaching him how to dial 911, but honestly, it's still a little beyond him. He will repeat it back to you, and show you the numbers when you are going over it with him, but if I go back later, he doesn't remember. So, we have everything programmed into the photo speed dial on my phone. We have a picture of an ambulance for 911 and he knows for now, that he is only allowed to press that one in an emergency, which we have explained what an emergency would be.