I have Cingular service. I want to buy a new unlocked phone from ebay, and put my current sim card in it. Then I want to go to Cingular and get a second line activated and get whatever free phone they give me, and put that sim card in my original phone so my wife can use it. Will this work? Current phone is LG F9100, and I want to get an unlocked F9200 (doesn't come with a sim card).