This is a tough one because so many children have mobile phones these days, so I can understand you feeling hard done by. Some parents are perfectly happy to let their children have every new gadget available, whereas other parents (like yours) may feel that it’s not appropriate until you reach a certain age.
Have you asked your parents why they’re unwilling to let you have a phone? It may be that your parents feel that a mobile phone is just too big a distraction for you to have unrestricted access to all day and that it will interfere with your studies. Another reason could be the risk of cyber-bullying, which can have devastating effects on a child’s confidence and self-esteem.
Adults are also concerned that when children have a mobile device, they stop communicating in other ways, and that the phone just takes over. It could also be a financial issue – mobile phones are expensive and go out of fashion so quickly that some parents can’t justify the expense.
Once you know what your parents’ objections are, you might be able to agree a compromise. Would they consider letting you borrow one of their phones on an evening for an hour or so? (After all the homework is done!) That would help you to build up some trust that you don’t want to be on it the whole time and your parents might then consider letting you have your own phone. If it’s a question of money, perhaps you could look for a second-hand phone and ask for it as a Christmas or birthday present.
I think if you approach your parents with some reasonable proposals, even if they don’t agree, they will see that you’ve acted in a mature way and they might then be willing to reconsider the whole issue in the not-so-distant future.