Activating tethering on a Docomo ROMs designed for FOMA 3G handsets will force a switch to a different APN, the use of which automatically triggers an additional charge to FOMA users (Xi users are not charged). At the same time, viewing the APNs is disabled. So if a FOMA handset is used with bmobile or Xi, trying to tether kills it's data connection, and with a FOMA handset, it will disable sp-mode, meaning users have to wait to have their mail randomly delivered to strangers or their passwords surreptitiously reset until after they finish tethering.
If your contract allows for free tethering, you can fix this by flashing a custom ROM or googling for
tether_dun_requiredin the proper context. (Sorry, I'm not going to post exactly how to do it since it could also be used for free tethering.
- ROM of your choice and Google Apps if not included in the ROM. I am using this one.
- clockworkmod recovery for the GSM version aka Maguro, if you don't already have it. (You don't need ROM Manager. "Touch recovery" or "normal recovery" is based on your preference.)
- Latest Docomo Radio for the SC-04D, currently SC04DOMLE3 from this thread. I chose the clockworkmod (cwm) flashable version. The other requires flashing with fastboot.
ProcedureWARNING: this will void your warranty, possibly wipe all your data, and could destroy your phone. Do it at your own risk!
This is but only one way of doing it. There are other ways that may not require wiping all the user data. I didn't care about wiping the user data because the phone was already in a wiped state after being sent in for service. I'm also not worried about the warranty, which is already void. This also assumes the phone is totally stock.
This requires all necessary drivers for the phone, ADB, and fastboot from the Android SDK. If you don't know how to install these, stop now. The SDK "platform-tools" folder should be added to your path.
If the phone is on, copy over the 1) ROM, 2) GApps, and 3) Radio files to the sd card. Enable USB debugging. Open a terminal windows on your computer and reboot the phone to the bootloader:
If you have not already, unlock the boot loader, which will wipe all user data.
fastboot oem unlock
Flash clockworkmod recovery, replacing the file name with the one appropriate for the one you downloaded. Include the path to the file. (Stock Google ROMs will overwrite the recovery on reboot, replacing CWM with the stock recovery. Custom ROMs do not do this.)
fastboot flash recovery-clockwork-188.8.131.52-maguro.img
Use the volume keys to select recovery mode and hit the power button, then back up the current system image (data would have been wiped if you just unlocked the bootloader
Go to advanced and select wipe dalvik cache
Reboot back to boot loader, wait for the fastboot screen to show up, and do a full and complete wipe of the system, data, and cache partitions.
fastboot erase system -w
Go back to recovery and flash ROM, then GApps, then radio