Regulating former telecommunications monopolies has often been legally and technically complex. Among other options, incumbent operators were mandated to share, sell or split their infrastructure thus encouraging market entry. Given the importance of broadband technologies, competitive access has become a policy priority. We use data from 167 broadband markets over a period of 11 years. Firm and intra-platform competition on the incumbent’s legacy network (Digital Subscriber Line) accelerate adoption of broadband, whereas competition over different access technologies does not. The duration of the different regulatory effects shows that simpler network changes have a long-lasting yet delayed effect compared to technically demanding ones.