Users need to have messaged or called (in or out) to be counted.

Users from large-area countries (RU,CA,US,CN,IN,BR,AU and EU) without more precise geolocation information (beyond country-level) are filtered out.

US APO/FPO users are not filtered but rather kept mapped to (0,0)

Bubble size is proportional to number of users in the cluster, not the geographical span of the cluster.

Users belong to the one cluster with the center closest to them.