I can't figure out how to unlock my new (second-hand) Samsung sgh-a737 phone. There is an "unlock" at the bottom left corner of the display which presumably locks the display while the phone is not in use. What do I press to unlock it?

Open the Samsung A737 page at any of these sites: My Unlock Code, GSM Liberty, Unlocking.com or Mobile Unlocked. All four of these are pay sites. Mobile Unlocked and GSM Liberty offer money-back guarantees in case the code will not unlock the phone.

Remove the Samsung A737's battery. When the site you chose in Step 1 prompts you for it, type in the International Mobile Equipment Identity (IMEI) number from inside the Samsung A737's battery compartment. Every site in Step 1 needs the IMEI to generate an unlock code specific to your phone. Pay for the unlock code. In case you do not use a credit card, most of these sites will accept a PayPal payment. You will receive the unlock code by email, usually in a few hours, depending on which site you chose.

Slot the old carrier's chip into the battery compartment, in case the unlock code will not work without it: some unlock codes are network-specific. Put in the battery and close the battery chamber.

Enter your Samsung A737's phone mode. Type on your keypad the code precisely as it appears in the email. If you receive the unlock code "A5966J Send" for example, then type in 259665, and then "send" the code to your Samsung A737 by pressing the Talk/Call/Send button.

Slot the new network's chip in under the battery. Make an outgoing call to test if the phone is now unlocked. If the call does not go through and a chip or SIM error message pops up, repeat Steps 3 and 4 a few times. If you still cannot make a call, contact the code provider so they can remedy the problem.