These days, with cellphone technology, most households do not have landline phones anymore and domestics seldom have credit on their phones.
Hide an extra phone in your house and load emergency numbers on it. Switch it on and make sure it is charged at all times. Always make sure that airtime is available. Teach your children and domestic how to use it and that it is only available for emergency situations. It can come in handy when intruders demand phones during a robbery or when there is an emergency when someone is home alone.