Problem is that most devices do not tell you if they are CMIA or OMTP, for instance neither LG TMobile MyTouch (LG -E739) nor any of the earbuds with microphones mentioned list their 3.5mm jack wiring. I have not found one that does clearly state which standard is used. All Android devices are not the same. After trying three different headsets with in-line mic that did not work:
Logitech Ultimate Ears 200vi.
I finally went to that infamous Radioshack and bought PointMobil 17-5432 which works fine. Actually it seems to be pretty decent quality and only $24.99.
Not only do devices not say which standard they use, some say they are compatible with iPhone, Blackberry (CMIA) and LG Android (OMTP?) making me wonder if they use adapters or if there is a software solution.
Bottom line. Be doubtful and check it out before leaving store. It would help if manufacturers were clearer and more specific and if TMobile offered more insight and compatibility tables or at least specify what standard is and maybe even offer a wired headset with Mic.