As of mid-2011 there were about 6 billion39 mobile subscriptions globally, and at the end of 2010 there were almost 4 billion mobile cellular subscriptions40 in the developing world with active SIM cards. The total IMT population coverage has increased over recent years but is heterogeneous, depending on the country. Indeed, the first areas with mobile broadband coverage were cities where the density of population is highest. Other areas are now being covered and refarming enables operators to use the bands below the 1 GHz frequency, which provides properties for larger cell radius than the bands around 2 GHz.