Historical British telephone directories have recently availed themselves as disaggregate sources of population data for time periods not covered by other popular sources. Having devised a comprehensive processing pipeline to prepare these data for further analyses, this paper explores what they could uncover about British historical demography. For one, the differential uptake of telephones across space and time, owing to changes to its affordability and applications, reflects socioeconomic disparities. Being a data source that spans decades, it also lends its application to the study of intergenerational inequalities through the unit of family groups, as indicated by surnames that subscribers bear.