Thanks everybody, I was looking for this specially to use my phone with another carrier. I bought my phone without contract and in theory my carrier should give me a code to unlock it..the problem is that I don't have my purchase proof because I got my phone more than a year ago...and it seems their policy only allow then to unlock phones with a ticket/invoice and some I.D.
I want to try my phone in another network because lately I am having signal issued, I also loose data transfer for brief moments, so I was wondering if is a network problem or my phone.