Motorola H-500 i have a motorola h500, and for some reason when i hook it up to my ps3, i can hear people through my headset but i cant talk to them..

On the H500 - press both volume buttons at the same time and hold until you hear two descending tones to ensure mute is disabled. Also double click the volume control on your computer to open the volume controls and make sure the microphone channel isn't muted.

go to your settings and make sure that the microphone is set to headset.

try reading this website
http://www.simoncells.com/manuals/Motorola/H500.pdf

This is a common problem with speaker phones as well since they (as is your headset) forced to switch back and forth so microphone and 'speaker' are not on at the same time to prevent feedback. The squeal from feedback would be far more irritating. Your previous phone in conjunction with your headset were simply (and accidentally) a better combination.   

0000 or 00000

;)

Try 0000

Contact Motorola and tell them the situation. They will send you new ear hooks. I've done this twice since they don't have replacement parts available publicaly

are you pressing L3 to talk?

hit the sound icon on your desktop rightclick it, go to Recoringtools turn down the microphone! As in the picture.
Im sorry its dutch :-)

Turn down the volume on the PHONE, not the headset. Motorola 325i w/ H500. Again, turn down the volume on the PHONE, not the headset. In my case almost all the way down.