Studies have shown that ethnic segregation is conducive to social segregation. With the advent of information and communication technologies, mobile communication can support non-local social interactions and reconfigure the network composition of ethnic groups. This study focused on the similarities and differences between ethno-national groups in the structure of their cell phone communications. Data for this study include a sample of 9,099 business customers’ mobile phone calls from an Israeli mobile operator and tested two theoretical explanations. The social stratification approach predicts that mobile communication will reflect the patterns of spatial and social stratification that exist in society. On the other hand, the social diversification hypothesis expects that residentially and socially segregated minority groups will take advantage of mobile communication to diversify their social contacts and to engage in mobile communications with non-local and out-group ties. The findings suggest that in the information society, both structural conditions (the stratification approach) and social incentives (the diversification approach) are relevant for the understanding of inter-ethnic mobile communication, and structural conditions reduced inter-group mobile communication patterns. The Arab Israeli minority was more likely than the Jewish Israeli majority to engage in mobile communication with non-local ties and out-group members. Yet, structural conditions reduced inter-group mobile communication patterns. The theoretical implications of the findings for inter-group mobile communication are discussed.