As far we knew, this number is collected on the basis of demand-side surveys. When such surveys were not available, “administrations” (Ministries or Regulatory Agencies tasked with the job) would submit estimates, based the number of subscriber and a multiplier. We’ve spent untold hours on the phone, trying to wheedle these numbers out. We even published a peer-reviewed article proposing an alternative (and, in our opinion, superior) method. But little did we (and the peer reviewers, and those collating the data at the ITU) know.