TTY's could only communicate with other TTY's until the late 1960s when Marsters and Saks developed the idea of having phone company operators take TTY message and relay them by voice to hearing phones, and vice versa. One early attempt at this did not last because of the cost and the noise the machines made, but the concept led to a requirement of a similar service in the Americans with Disabilities Act in 1990 which is available nationwide today.