Even though service-orientation has been widely applied, there still is a lack of systematic and tool independent development methods. Partly due to that, little attention has been paid to accounting for variation. When developing a service-based system, it is important to identify which types of variation are relevant for the project and when is the right time to model them. If the variation needs are not recognized or they are ignored, it may hinder applicability and reuse and results in inflexible systems. If they are considered too late, it may require a lot of redecisions and rework.In this paper we explore variation needs in terms of the development process of service-based systems.This study results in a categorization of variation in service-based systems.We illustrate the categorization in a small example in telecommunication area.