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.
Children should ride in a safety seat with full harness until they weigh 40 pounds. Children over 40 pounds can be moved into a booster seat using the vehicle lap and shoulder belt. It is recommended they ride in booster seats until age 8, or 80 pounds, or 4' 9' in height.