TMO - here's a dedicated thread: http://www.flyertalk.com/forum/trave...-coverage.html

Basically, unlimited data at edge speed [in many countries in Asia, 3G or HSPA+]. Free text among 120 countries and $0.20/minute call. Read the thread and you'll see it works well from China down to Indonesia.

VOIP works well most times, I've used skype, Line and google voice, about 80% success rate.

If you do decide to go with local prepaid, visit the technology thread for specific country threads. MODERATOR - may want to move this over to technology thread.