The Cell Phone modeling task centers on a Fermi real-world estimation question. The task and rubric can be used at different grade levels to focus on the modeling process and classroom community. Finding time and space to engage students, especially novice modelers, in mathematical modeling can be a challenge, yet the benefits of modeling are numerous. The authors developed a task that is a good introduction to modeling for students and teachers for whom modeling is new and a useful alternative for experienced modeling teachers who are looking for something different. The variation on a Fermi question -- a question that requires the estimation of a large quantity -- and rubric that the authors developed have multiple uses across middle school and high school, within and beyond mathematical modeling.