Call your cell phone
carriers customer service and they may email
you the unlock code and instruction for free within 24-48 hours. Tmobile did this for me several times on different phones
Tmobile will send you the unlock code and instructions via email
for free for their customers within 24-48 hrs. But you have to call their customer service (US) 800-937-8997. I tried emailing them initially but no response. When I called they were so accomodating and didnt even ask why I wanted the phone unlocked.
Once they send you the code its simply inputting the code they provide. However to do this you must first put in a non tmoile sim. As far as I know this is only cingular or a foreign pay as you go sim card. Luckily I had a foreign sim that I saved on a prior trip as I have other unlocked phones and this worked for me. None of my friends had cingular so I could not use their Sim to do the unlock code on my phone. Nextel, Sprint and I think Verizon also dont use sim cards.
Alot of cell phone stores and kiosks will also unlock any cell phone for you for about $30.00. You may have to leave the phone with them and pick it up later like an hour or two later if they are busy.