The Four-corner model aims to finally solve the scalability issues of the former two models by uniting the service providers in a network. Each company, again depicted in blue in the figure below, is free to choose the service provider which best meets its requirements. Each company can, similarly to the Three-corner model, setup a connection to its service provider with a communication method of choice (e.g. FTP, e-mail). The service providers are all connected to each other via the model’s inner-network, meaning that each service provider can communicate with all other service providers. The service providers are responsible for translating all incoming messages in a common format, in our case the SCSN communication standard. The translated SCSN message is then send to the service provider of the message receiver, who translates the message and finally sends the message to the receiver.