The official jammr servers work for people around the world. They are not very sensitive to latency. You can jam with people in Japan, Australia, etc without running your own server.
If you decide to build Wahjam (the software that powers jammr), take a look at server/example.cfg and the server/wahjamsrv binary that gets built. To build, run qmake followed by make.https://github.com/wahjam/wahjamhttps://jammr.net/opensource.html