Hi, We have 2 ATT lines with Iphone, not eligible for full upgrade. The 3nd line with dumbphone is off contract. I plan to use 3rd line to get the new iphone but then replace it with the dumbphone and put the new iphone on the 1st line. How should I go about transferring phone numbers so at the end the dumbphone will be back on dumbphone number and new iphone will be associated with the old iphone number? Will att accommodate me in providing proper size of the sim cards? And if my math is correct this will be much cheaper than simply paying an early upgrade fee of $250 and loosing eligibility for next upgrade cycle. EDIT: clarified that I have 3 lines in total on the ATT family plan. Thx!