What should i do about the CELL PHones?

i have 6 kids- my oldest Leslie has a cell phone- then annie jo has one- then I have twins Max and Mandy (there both 12) They want cell phones for christmas BOTH of them me and my husband has cells and my husbands a Surgical Doctor and I am a Pediatrician so we have enough money and my older daughters will get angry if i get them a cell because they did not get one till 16 and i do not want to pay for 6 phone bills!! But... they are both very responsible way more then my too oldest! i think they deserve one and i told them if they got straight A's for 2 sem. in school i would think about the cell! What should i do?