It’s a little bit late, though.
I had used Nokia N82 with Softbank Mobile’s SIM card as a main mobile phone so far. I had told my friends the phone number of it. But it had been kind of inconvenient because it had had narrower signal reception areas than the mobiles of NTT DoCoMo so if you had gone underground or deep into a big building you couldn’t have had it communicated. More than that, (it’s the situation peculiar to Japan, though) you can send SMS only to the mobiles of the same carrier as yours. Most of my friends had NTT DoCoMo mobile phones, so I’d wanted to change the carrier of my handphone into NTT DoCoMo.
NTT DoCoMo had released Samsung’s Galaxy S handphones in November and they had been very attracting for me, but they had been in so short supply in those days that I couldn’t have got any. I’d given up waiting for one.
At that time, Japan Communications had begun releasing b-mobile’s micro SIM cards together with unlocked iPhone4 imported from Hong Kong. JC had been selling the imported iPhone4 to its customers on hire purchase. JC was providing mobile phone service using NTT DoCoMo’s network, so if you had a mobile with b-mobile’s SIM card installed you could use it in almost the same manner as NTT DoCoMo, including sending and receiving SMS to and from NTT DoCoMo’s phones.
That’s why I purchased b-mobile’s micro SIM card called "b-micro talkingSIM" and iPhone4. Prior to the purchase I had cancelled the contract with Softbank Mobile and had the phone number used in it reassigned to the new micro SIM card so that I could use the same phone number as that I had told to my friends.
The b-mobile SIM card was completely the same as NTT DoCoMo’s, but you had to set up b-mobile’s original APN, user name and password manually to the iPhone4 to have it activated. Besides, you could set up configuration of tethering, which only JC allowed its customers to use while NTT DoCoMo didn’t.
I cut the micro SIM card off the frame, put it on the micro SIM card tray of the iPhone4, inserted the tray into it, plugged it in my MacBook Pro where iTunes was operating, and turned its switch on.
A couple of minutes later the iPhone4 was activated with no problems. Applications were downloaded from iTunes to it, and the sync of other data including contacts and email accounts was successful. Of course, SMS can be sent to friends with NTT DoCoMo mobile phones!
A gadget: it’s Q-SIM Dual SIM Card, which allows a normal SIM card together with a micro SIM card to be installed in iPhone4, so that you can use two different SIM cards in one iPhone4. Two SIM card slots are connected with a thin link, one of which accepts a micro SIM card and the other a normal SIM. By sandwiching the micro SIM card plate of it with a micro SIM card and a micro SIM card tray, putting it into iPhone4’s micro SIM card slot and folding the rest of the link so that it reaches the back of iPhone4 which is put into a included case, you can use two different carriers in one iPhone4. Auto-switch between the two SIM cards is also available.