To return to docomo from a cheap SIM

There is no reproducibility, and it is still a mystery what happened, but I will introduce it as a record.

Many of you know how to set up a cheap SIM on your iPhone. Insert a cheap SIM into your iPhone. Then connect to the internet via Wi-Fi. Next, install the "APN setting profile" from the SIM vendor's website. Then the network settings are completed and you can connect the iPhone to the Internet.

Cheap SIM is because the iPhone does not have a gateway (APN) setting that serves as a connection window from the mobile phone line to other networks. You have to put that setting information in a file called "profile" and tell it to the iPhone.

Then, what should I do to change the SIM to be used from a cheap SIM to a major carrier's SIM such as DoCoMo? The correct answer is to delete the cheap SIM profile and insert the SIM you want to use in your iPhone.

It should be, but for some reason I deleted the APN setting profile of the iPhone 6s that was used with a certain cheap SIM and inserted the Docomo SIM, but I couldn't connect to the Internet. is.

Since the cheap SIM profile has been deleted from the iPhone, it is not displayed where the APN settings are. The carrier setting information displayed in the "Information" - "Carrier" column is "Docomo 31.0" (this column does not change for cheap SIM or docomo SIM).

I can't connect to the internet, even though the display on my iPhone is normal. I have just raised my hand. Call DoCoMo's support number "151", tell them the current situation, and ask for a solution.

"It's strange, normally you should insert a USIM card and reboot to switch to DoCoMo... If that doesn't work, there's a way to reset the network settings on your iPhone. Would you like to try it out?"

I see, the iPhone has a way to reset the network to the same state as when it was purchased. The menu is "Settings" - "Reset" - "Reset network settings".

With this procedure, the iPhone recognizes the DoCoMo SIM and is now able to connect to the Internet correctly with LTE. I am grateful to Docomo's support sister.

Anyway, this "cannot communicate even if docomo SIM is inserted" problem will not be reproduced after this. It's strange. I'm trying various things, such as inserting a SIM from China Unicom and switching to LINE Mobile. What happened is still a mystery.