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.
Booster seats are for children who have outgrown convertible or toddler seats. Booster seats are for children who are 4 to eight 8 old, weigh 40 to 80 pounds, and are less than 4 feet, 9 inches in height. You can use a booster seat until an adult seat belt correctly fits the child without use of the booster seat.