Ask HN: Communication between locations and avoiding existing infrastructure

Hi I'm thinking about a possible project and Searching for an answer.

Communication between distant locations 300 to 700 kilometres apart by avoiding existing infrastructure (routers, cables, DNS).

What I need is standard TCP/ip services (web, ssh, samba,), voice, video would be nice. What technologies could be used and how reliable and safe (from outside intrusion) are they.

What comes to mind is: To use modem (still uses existing phone lines).