This study examines (dis)similarities in the cell phone communication structures of two ethno-national groups. A large sample of business customers’ mobile phone calls from an Israeli mobile operator and two theoretical explanations are tested. The social stratification approach portends that mobile communication will mirror society's spatial and social stratification. The social diversification hypothesis meanwhile awaits that residentially and socially isolated minority groups (in casu the Arab Israeli minority) will deploy mobile communication to vary their social contacts and to communicate with non-locals and out-groups. Both approaches appear apt for the comprehension of inter-ethnic mobile communication, and structural conditions decrease inter-group mobile communication patterns.