Network inventory and CRM systems should be an excellent source of information for regulatory authorities in a review of the business connectivity market. However, in practice, service provider data quality is often poor, and cleaning up these data sets can appear daunting. Referring to recent work by Ofcom as an example, we show that with the correct tools and techniques, these issues can be overcome. Regulators can then obtain a detailed understanding of the market, including geographic variations in competitive intensity.