A simple Google search will reveal a lot of websites with results on how to unlock your iPhone and even how to jailbreak iPhone 5 cell phones. However, it would be ideal if you stood away from companies that are claiming success for some unlocking and jailbreaking software that we have never heard of.
Some companies that activate mostly in the online industry can scam you out of your money and will not even be able to a jailbreak or unlock your iPhone. The main steps that you need to follow begin with the downloading of the proper software from a top-rated unlock or jailbreak website. It is best to put the device in airplane mode as you are performing the unlocking or jailbreaking process. Take out the SIM card and insert the SIM card you want to use with your iPhone if you are unlocking the phone. Make sure the wireless feature is turned off and then you can take the iPhone out of airplane mode.
Once the airplane mode has been deactivated, the phone or look for networks on its own, in order to activate them. If you see any EDGE networks working on your phone, then you have to switch off the phone and follow the next step which implies to switch the phone back on and then it will look for bars of signal. If new signal is found, then your iPhone has been successfully unlocked and you can perform a test call.
Remember that in this entire process the first thing you need to do is to look for unlocking software (or for jailbreaking software if you want to jailbreak your iPhone) which is safe to use. The software that is not legit could end up blocking your iPhone and you will never be able to use it again with any SIM card.