Interaction designers for mobile phones mainly focus on displays but have only little knowledge about sensor characteristics. Beside multitouch input, mobile devices provide versatile possibilities to interact in a physical, device-based manner due to their built-in hardware. Even though such interactions may provide many advantages in everyday life, they have limited visibility in interaction design. Interaction designers are seldom experts in gesture and pattern recognition and even prototypical implementations of simple mobile-based interactions need advanced technical knowledge. Hence, the potential for designing mobile device-based interactions is often not fully exploited. To contribute to a common knowledge of mobile device-based interactions, this paper proposes Mobile Spaces. This model aims at supporting designers of mobile applications to broaden their view on interaction possibilities with one or more collocated devices which go beyond the screen. We discuss the applicability of Mobile Spaces by means of several examples from research.