Based on the high level description given in the article it seems to be related to enum lookup or net number. It's basically a kind of DnS lookup for phone numbers used for sms routing. Also this is used for routing sms that are belonging to a user to an application (in case you want to reroute your sms to an application). The company will change the enum code for the number to a.code that belong to the company and reroute the messages to its services. So the hack is not really a hack in a sense that it work as intendant, the safety net is missing though. The company operating the enum is supposed to check the legitimacy of the change.