Legal to record my cell phone conversation ?

Well, I suppose if you never disclose it anywhere, you wouldn't have to worry about the legalities. It's illegal to record a conversation without a notifying "beep". You do not, however, have to explicitly say that you are recording, you just have to have a "beep" at some point, however you decide to make that noise. The other person is supposed to know that the beep means they are being recorded.