Does factory resetting a phone remove the "unlocked" state

[JackHammer]

So basically I bought a Samsung Galaxy S from Tenerife, unlocked to any network (SIM Free) but it still has Movistar branding on startup and shutdown. I am having problems with enabling data on the phone and have been advised to factory reset. Does anyone have any idea if factory resetting a phone removes an unlock? Thanks

[Deunan]

No as the branding and basic setting is inside the firmware. You'll need to flash that to a generic one first.
(at least that was the case with all dumbphones I've ever had, doubt it's any different though)