Enterprise application integration is often described as the use of some toolset that enables the rapid integration of legacy, packaged, and new applications into new business solutions and thus providing more flexibility. This paper is based on sd\&m experiences in a project to integrate two packaged applications from SAP and Siebel. We present all architectural aspects of the developed solution with the main focus on the technical software architecture. We show that EAI toolsets provide technical software for the integration but error handling, process control and more important business logic has to be built within the project.