Broadband is seen as a vector of economic growth and social development. In the developing world, mobile technologies are widely adopted and mobile broadband is progressively rolled-out with high expectations on its impact on the countries' development. We highlight what the determinants of mobile broadband use are in four Sub-Saharan countries. Using micro-level data coming from household surveys over 5 years, from 2013 to 2017, we show that SIM card ownership and being part of an online social community has a strong positive impact on mobile broadband use. We also highlight a positive correlation between digital inclusion and financial inclusion as mobile money users and bank account users are found to be more inclined to use mobile broadband. However, beyond apparent similarities, mobile broadband is used in different ways according to countries specificities. For instance, among the non-mobile owners in Nigeria, the unemployed are the most likely to use mobile broadband, most probably for job search practices, while it is rather used by students for information gathering in other countries. Finally we show that those excluded from mobile broadband use are the eldest, those with the lowest level of education, and women.