I’van iPhone 4 locked to a contract with Swisscom and a Samsung Galaxy3 which I paid for so is not locked and I use this when travelling so I can swap SIM’s. Love it and its way better than the iPhone. Even elder son now wishing he’d gone with Galaxy over iPhone.
Just bought a Samsung something or other for the youngest. Cost CHF 150, not locked and what’s brilliant is it takes two SIM’s so he has his Swiss and S. African one both in saving swaps and possible losses. He can Tweet, Whatsapp etc and its quite small. May go for one myself as that’s all I use them for!