Cities provide an excellent platform for gathering and detection of massive amount of data from cities and citizens. Emergence of new digital technologies inspires not only city governments but also city residents, researchers, companies and other stakeholders in discovering and creating new innovative solutions to solve urban challenges and improve peoples´ everyday life. Developing novel Internet of Things (IoT) solutions for cities and citizens requires facilities where IoT applications and services can be tested and experimented. The challenge for many smart-city test and experimentation platforms (TEPs), like living labs, has been the lack of sustainable value creation model. This has caused many experimentation platforms to perish after the ending of external funding. A vision about how to construct a robust and continuous IoT test and experimentation platform, as well as instruments for it, is required. The IoT service experimentation platform (IoT SEP) framework presented in this paper provides guidelines for this effort. IoT SEP consist of ten dimensions relevant for establishing a sustainable IoT SEP in smart cities.