A recent blog by number range experts Biaas argues that both international revenue share fraud and wangiri are increasingly associated with number ranges that have been allocated for use, but which have no genuine use.
…many destinations which appear in international carrier price lists are not actually used for normal international traffic termination by consumers and businesses, and this can be for a multitude of reasons. Examples include license revocation by national overseas regulators, operators ceasing to trade, operators selling local number ranges to smaller operators without networks, or even an operator never building a planned network in the first place. We note that many allocated ranges in exotic sounding destinations have been kept in reserve for years, still not used by new customers who never materialised. Some ranges are even kept alive in national regulatory documentation and carrier price lists by using confusing banners and labels such as ‘value added services’.
Apparently these ranges are especially profitable for criminals.
…these destinations are often flagged up as being slightly more expensive within carrier price lists, giving fraudsters more value per call.
You can read the full blog here.