Ray Tomlinson didn't invent email, but as the engineer working on ARPANET in 1971 who sent the first electronic message from one computer to another he is commonly considered the man who implemented email. Early on he watched it grow as a replacement for telephone calls because "you didn't have to have someone there to receive the call." He predicts future applications will convert messages in other channels into email: "so you send an IM to somebody, and if they don’t respond it turns into an email-like thing without any intervention on your part."