I got a phone as a gift [a second-hand one, I now know] so quite naturally I wanted to customize it to suit my needs but there's this annoying request for me to enter a security code which even the giver of the gift doesn't know. Someone told me that there was some software one can use to reset a phone to it's original factory settings after which I could you know, do anything I please with it. Anyone know of such software?
Pretty much. If it's an apple product, then it's usually easy to do it, but a lot of the old phones is a matter of what model it is, because some just don't work with the usual ways.
We do need to know what phone it is, as well as the operating system/firmware that is on it. But in general, there really isn't a "software" per se that unlocks phones. Most of the unlocked phones either come from the factory unlocked, or the carrier unlocks them themselves. To get a carrier unlock, you could ask your carrier, obviously. But they won't unlock unless you are a customer, are out of a contract, and are in good standing with them. There were thousands of carrier unlock services overseas that would call/email the carriers and just bombard them until they eventually unlock their phones. These services were dirt cheap, like $2 USD for an iPhone. There were also carrier unlock services that would someone find a way into the carrier IMEI's database and change the status to unlock these phones. It was a very easy process, just pay $2 and you'd have an unlocked phone. HOWEVER, the carriers finally got wind of this. AT&T (the biggest GSM phone provider in the United States) closed all the backdoors for the unlocking process. You can't even do it by phone anymore, it is all done online with your account. So they are very, very strict on unlocking procedures because it was being taken advantage of by so many. They shut all this down last October, so this is all very recent. The only other way to unlock a phone like an iPhone would be to jailbreak it and then find a way unlock it yourself, but again this isn't a software. With each iOS update it cancels out the jailbreak. And currently, there is no unthethered jailbreak for the latest iPhone/iOS.
Depending on where you live, mobile phone repair shops can also help you out. Or at least should be able to.
Simply do a google search for "factory reset" followed by your phones model number. There should be a combination of keypresses you can use which will completely wipe the phone
With Android phones its often something along the lines of holding down your volume and camera buttons while you restart the phone. This won't unlock the phone, but it will often take you to a factory reset option which will reformat the phone back to factory settings. It will also ask you for your Google account login after doing this. For jailbreaking your phone you need to do a google search for the model. I will warn you though that this can sometimes cause updates to not get pushed out to your phone. I had this problem with my Droid Bionic and had to get it replaced by Verizon because I couldn't download and install the update they were pushing out for it (I didn't tell them I unlocked the phone of course).
Factory reset and unlocking are two completely separate things. A factory reset erases all the memory while an unlock makes it so that a phone can be used on multiple GSM carriers. A factory reset does not unlock a phone. Phones either come from the factory unlocked, the carrier unlocks the phone, or someone does some tweaking with the IMEI number in the carrier's database. It is actually illegals in the United States to unlock under-contract phones as of January 26th, 2013.
There a wide range of software available for nearly each type of phone. Depending on your phone you will definitely find a software to rectify your phone to meet your desired condition. What you only need to do is to visit any of your local stores and ask for help and you would be helped to solve such problems.
I think it is a bit cheaper to search for ways you can factory reset your mobile phone rather than investing so much paying for a thing you can do by yourself. Google has everything and by doing your research perfectly, you can be sure of saving huge sums and still meeting your desired target of having a functioning phone.