Unlocking a Samsung mobile phone....

[Decembersangel]

I am being gifted a locked Samsung mobile phone (I don't know which network it is locked to) and I am asking to see if anyone has any suggestions as to how I can unlock the phone without having to pay to do it i.e. from my laptop, via the phone etc??
My 1st thought is to do the 'return to factory settings' step as surely that will remove ALL limitations/data... won't it?? as surely it didn't come from the factory already locked?? (Opinions on the internet differ on whether this will work or not!)
Does anyone know of any websites that will help me unlocking it??
Any and all suggestions will be greatly appreciated!
Ta Kindly x x x

[MSF]

@Decembersangel I will admit at the outset that I do not know an exact answer. However, it would probably end up cheaper and less risky to either approach the original network or else get a local phone shop to do the job.