People cant hear me on my bluetooth

i have a blackberry curve 8900 and a motorola h700 my bluetooth connects to my cellphone i can hear everything people are saying to me but they cant hear a word im saying. i tried it with 2 different h700 the silver one and the black one and its the same problem. i also tried it on another blackberry 8900 and same thing. is there some setting that would cause the other party not to hear me?