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 ages 8 until 16 who weigh at least 80 lbs. or are taller than 4 feet 9 inches must use a seat belt or appropriate booster seat. Children ages 4 until 8 must ride in a booster seat or appropriate child restraint system, unless they are taller than 4 feet 9 inches or weigh more than 80 lbs.