In this paper we describe the usage of physical posters as gateways to mobile services that are related to advertisements and information presented on these posters. In our approach the user can interact through a mobile device with services that are represented by a poster. Our aim is to create a system that allows seamless and natural interaction of users with posters. Our work is based on a requirements analysis. We investigated placement and physical accessibility of posters and the behaviour of people waiting in public places. Based on these observations, additional interviews, and an Internet questionnaire, we extracted scenarios and present an overall architecture of our system. A prototype, taking these results into account is outlined at the end of the paper.