About my keitai

I have two cell phones. One is Docomo, and the other is Softbank. I mainly use Docomo’s cell phone. It is black. I use it just for a month. I really like it because it is very useful for me. I seldom use Softbank’s one. I want to increase “tadatomo”. I have registered only tadatomo in my Softbank and I use only calling function. But I have been charging it about for two month. I feel it wastes costs. I pay Softbank’s charge on my own, but I have my mother pay docomo’s charge.