Why not just use the phone

Telstra has introduced an SMS->Voice service - you can send an SMS text message from your mobile to a fixed line home phone When the message arrives, your phone rings, and a computer voice reads the message to you. Which begs the question - why not just ring the person up to start with? I guess I can see the usefulness - a company could use it to communicate roster information etc to people without mobiles. Although I didn't think there was a cat or dog left in Australia who doesn't have one.