Internet facilitated Global Connectivity
You can dial up your friend directly simply by putting in his/her callsign into your radio without knowing his or her current location or what D-STAR repeater they are currently using. Repeaters can also be linked together as needed by operators on air to form a wider area conference or system administrators can link repeater gateways together to link all voice & data from multiple repeaters together. Operators can also talk to a repeater via one band and be cross banded out another band on the same repeater. Repeater systems can be interconnected via "reflectors" which are essentially servers on the Internet with appropriate capacity behind broadband Internet links that interconnect many repeaters together.
(*Digital Smart Technology for Amateur Radio)