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.
Six seats had the more reasonable minimum weight limit of 40 pounds. This makes sense because the growth of children between 30 and 40 pounds occurs at a slower rate than when they are infants. An average 40-pound child is typically closer to age five, a much safer age to consider making a transition to booster use.