As a result, we initially observe increasing returns on growth (see Roeller and Waverman, 2001, Shiu and Lam, 2008). While Roeller and Waverman (2001) associate "critical mass" with near universal voice telephony penetration, we are starting to identify this phenomenon for broadband as well. Research points to the fact that in order to achieve an important level of economic impact, broadband needs to reach high levels of penetration. For example, Koutroumpis (2009) found that for OECD countries the contribution of broadband to OECD economic growth increased with penetration (see Figure 3).