Scratch

That would be hugely complicated. Something like cleverbot either learns from what people say to standard questions/statements and then says something similair if it gets asked/told something similair. Or you have to teach it how language works, give it at least the vocabulary of an average human (1000s of words) and you'd have to teach it grammar. Trust me, that would take forever. If you mean somethign like a computer sending you messages to your phone or similair device, as far as I know, it's impossible (without hacking scratch or building an add-on).