If those that you are connected to can't hear you but you can hear them it is probably not a service area problem.
A few things you can try:
If all else fails, you may have a hardware problem, call CS and see what they tell you. They may send you a replacement device.
- Try a battery pull and see if that resolves the problem.
- Check your settings and be sure that they are all OK.
- Just in case, call *228 opt 2 (I'm assuming you are vzw, check your carrier if not) this will update your PRL files which may help.
- If none of these work, wipe and reload your device with the same OS you now have. If you don't know how to do it, search the forums as there are lots of threads that describe how to do this.