About my cell phone

I use DOCOMO. I've had DOCOMO's cell phone since a freshman in high school. I've paid 8000-yen every month since I go to university. I pay on myself, so I want to cut down cost. I use i-mode and mail than calling.
And now, I'm interested in i-phone, because I want to listen to music everyday and I want to use internet for easy.By the way, I don't have Softbank's cell phone, but I want. My friends have it and DOCOMO. Because it is cheep calling, however we can only call during AM: 2:00~PM: 9:00. If I have it and call to my friend who has Softbank, we don't spend money. So I want DOCOMO to call free, who use DOCOMO.
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