New Hampshire

In 2016, New Hampshire was swallowed entirely by a fog that stopped at the state borders. People who were inside New Hampshire when the fog started or who traveled there for any reason have never been heard from again.

Several expeditions were made to understand what happened inside the fog. The first expedition led by the Vermont National Guard disappeared without a sign. The second expedition by the Massachusetts National Guard were bound with ropes to make it possible to extract them in case contact was lost. All of them had to be dragged out in a comatose state and haven't woken up since then. All expeditions after that had the same problems.

Following the fog
On birthdays, holidays and days of personal significance, every person across the world who was close to someone lost in New Hampshire receives phone calls from the state’s 603 area code. There is only about 80 seconds of silence, then the call ends.

Trivia

 * Malcolm receives a 603 call every year, who the person calling him is is unclear
 * According to the bonus content on the official tumblr account, the government issued a report stating that the fog is a toxic gas with a natural explanation. And that the 603 calls are made by a "malicious" unnamed hacker group.