how do flash or unlock a samsung galaxy s cell phone to get it to run on another network
I am assuming you are talking about a phone that was under contract to a carrier as those would be locked. A fully paid for phone should not be locked to a single carrier.
You will need to get the unlocking code from your carrier, which they should provide as long as your account is up to date and the contract for that particular phone is satisfied. Some carriers may provide you with an unlocking code before the end of the contract provided you have a good reason like traveling outside of their coverage area.
Once they give you the code, you put the new sim in the phone, turn it on and it should prompt you for the code. Once unlocked, you will never need to do this again.
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