Hi yes once you unlocked your Samsung Galaxy Siii mobile from network lock you can freely use it on any GSM network sim in it .If you want to unlock your mobile visit Superunlockcodes.com here they ask you the network name to which your mobile is locked and the IMEI number of your mobile .Then at last they delvier you code to unlock your mobile.
Thanks for your reply. I am getting mixed response.
I was told by Sprint Store rep that Samsung S3 is available in only CDMA chip or only GSM chip and Sprint only sell the one with only CDMA chip. Even if I unlock Spring S3 with CDA chip, I still cannot use my phone on oversea's GSM network because the phone does NOT have GSM chip at all. However, iPhone 5 does.
I love Android a lot and Im hesitant to switch to Apple. Can someone verify if the Sprint store personnel gave the right info? Thanks