This paper reports results of an investigation conducted to explore the status of Mass Customization in the mobile telephone industry and its implications for assembly operations. The study focused on the manufacture of two representative mobile telephone models at Sweden's Ericsson. The findings include the level of variety and customization in each model, where in the value chain this differentiation was implemented, and how it was conceptually, methodologically and technologically enabled. The analysis, aided by several frameworks from the literature, points to a changing role for assembly in this industry, and suggests research direction to meet future customized manufacturing challenges.