Passu

Passu is one of the last towns on the Karakoram Highway. It has no internet access and not all mobile networks have a good signal there. However, there's no police around and the Chinese camp (Chinese engineers working on the KKH) is convenient enough for hitchhikers. Go there at any time of the day (they start at 5am) and ask if they can drive you to Sost - they'll be happy to help.

If going the opposite way, you can only get a ride to Gulmit or Hussaini from where you must take a boat across a veeeeery long mountain lake.