Send Text To Phone

I have a Palm Treo 680. I just received two text messages and phone call telling me that I have sent text messages that just said, "Hi". I did not send these messages! I have no idea who these people are. However, they do not live in the region because we all have the same area code. Why and how could this happen? I am afraid that my cell phone hacked or someone is using my number somehow. If yes, how can I solve this problem? Thank you very much!

it may just be random people just randomly texting local number .. no hacker .. if yoru phone hacked or has a virus, then your phone will have phantom keys .. just random numbers being typed .. 1111111111111111111111111111111111111111 as ... that's all ..

how you can fix it ... you can not do anything but change your number ...