I see, well, the doctor knows very well his job, and I think folowing his advice must be the best thing you could do,
I've thinked about it yesterday, the reason why he doesn't allow you to communicate with them is maybe because when you do, the illiness slowly takes controll, for exemple, now you just hear voices, but when you'll begin to talk with those voices day after day, you'll begin to see faces, and those faces will become persons...
your doctor is a specialist, and he's been with you for a very long period, so he knows what he is doing, maybe you should talk with him about stoping the drugs slowly, and trying to controll your illiness by yourself,
he is the doctor, he saved your life from what I see, so you should stick to what he says,
and you should try to meet new friends, and build more real relationships, you don't need those voices to communicate, theire are millions of voices outside in this world !
and try to read more about schizophrenia, how people are dealing with it, if their are some patients who control it, if their are some people who communicate with the voices and are still controlling it
document yourself, I think the only answer you'll find is in books
and be always on your guard even if the voice is friendly, if it is friendly with you, doesn't mean that he will stay like that, or that he will be friendly with others