|N7 APN settings (Image source).|
Until now, we couldn't rule out a "server-side" origin for the problems that unlocked iPhone 5 users encounter when trying to connect to docomo LTE. This was because, except for those provided by docomo, there were no other LTE devices that supported docomo's primary LTE frequency (Band 1, 2100 MHz). We had two variables (iOS software and docomo servers), and one equation (Apple hardware), which is unsolvable.
We can now safely say that 3rd party devices are not subject to an across-the-board lock out from "Xi" LTE.
Prospects for unlocked iPhone 5S and 5C in Japan
It still remains unclear (due to lack of testing) what will happen when an unlocked iPhone 5S or 5C is brought to Japan. iOS is well known for disabling the ability to easily alter APN settings depending on the SIM card that is inserted. As mentioned in comments on another post, the iPhone Configuration Utility can be used to create configuration files that add new APNs, and this is used by some MVNOs to work around disabled APN settings. However, as I noted earlier, the docomo carrier bundle appears to prevent attaching to 3G and LTE networks with anything other than the sp-mode APN. If this is the case, it could render the configuration utility useless if these same rules are included on unlocked iPhones as well.
The sp-mode APN is filtered by IMEI number on the "server side." Only whitelisted devices (sold by docomo) can connect.
Nexus 7 LTE SIM options
The Shukan Ascii article compares different LTE SIMs in the Nexus 7. I'll briefly translate and summarize the contents in another post when I have more time.
In short, Docomo Xi SIMs work and are recommended by Shukan Ascii. You will need either:
- a subscription to docomo's Mopera ISP (mopera.net APN) or
- a contract with a docomo MNVO.
A contract change was also required to get a KDDI SIM to work, but as I suspected, coverage is not the best (though better than expected in the Tokyo metro area). Emobile SIMs are not yet compatible pending a firmware update.
Shukan Ascii weren't able to get the Softbank LTE SIM to work with anything except regular 3G, but they admit they didn't try very hard. I know of at least one person claiming to have softbank LTE and an iPhone SIM card working with Android.