All you need is a phone line! All phone lines have a constant flow of voltage, around 40-70 volts (up to 100 volts when it rings!), but you can't just plug stuff into it and expect it to work.
Children older than 5 and more than 40 pounds must ride in a booster seat until the child is 8 years old or is taller than 4 feet 9 inches. Anyone over the age of 8 must be protected by a safety belt.
Of the 34 booster seat models in our tests, 28 state a minimum allowable weight of between 30 and 33 pounds. Current growth charts, however, show that the average 30-pound child is about two-and-a-half years old, far too young to move a child out of a seat with a harness, according to our safety experts.