Unification of user-to-user messaging systems facilitates message exchange independent of time, place, protocol, and end-user device. This article describes an approach to unification that is based on introducing a middleware layer instead of employing gateways. It entails a single system that provides common services such as email, fax, and short messaging, but that can also enable novel services that current messaging systems can't support. The authors also describe how the model can be efficiently implemented on a global scale.