I have a jailbreaker iPhone 3gs, can i upgrade to Iphone 4 or 4S after resetting to factory settings on 3gs?
You can upgrade your iPhone 3GS to iPhone 4 or even iPhone 4S even after resetting it to factory settings. Resetting does not disqualify you, but jailbreaking does. Visit your carrier's outlet and ask about this.
yes if you restore you can upgrade when you upgrade they dont check your phone dont worry they only check your phone when theres something wrong with it thats when you should worry