iPhone passcode has been set after a factory reset - no iTunes to reset the phone
I recently purchased a new phone and following a sync with my old iPhone, and checking all was ok, i factory reset my old iPhone with a view to use this as my company mobile.
I have come back to my phone today and it has a 6 digit passcode which I did not reset.
Having looked for answers, I keep getting pointed to iTunes, but I cannot install iTunes on my mac.
Any advice please?