別の SIM を変えても症状は同じですね。
同じ様なトラブルJBiPhone3Gで有るみたい
IPHONE 2.1 3G can't receive calls!
http://www.hackint0sh.org/forum/f168/53749.htm
unlocked iphone can make calls but cannot receive calls
http://www.modmyi.com/forums/unlocking-activation/5280-unlocked-iphone-can-make-calls-but-cannot-receive-calls.html
