Fairphone 4 with the latest /e/OS installed via EasyInstaller works well in Japan

Here I would like to share my experience of using /e/OS on Fairphone 4 in Japan, where Fairphone series are not officially supported.

On the stock ROM, Fairphone 4 did not conduct IMS registration or recognize VoLTE networks of docomo and KDDI. It was unnerving, but it has been reported multiple times on the official Fairphone forum that after the stock OS on FP4 was updated to Android 12 the phone no longer recognized network connections in Japan, and I guess this might be the case.

I tried to establish network connections by editing APN configurations and resetting them without success, so I proceeded anyway to flash /e/OS despite lack of IMS registration and VoLTE provision.

After flashing /e/OS via EasyInstaller, though I needed to create an APN configuration for my MVNO as specified by it for KDDI, the phone was successfully provisioned for VoLTE :smile: It also recognizes 5G network as well, with working dual SIMs.

I tested some combinations, and here is what I got:

  • physical SIM card of KDDI (4G): works
  • physical SIM card of KDDI (5G): works
  • eSIM of docomo (4G): works
  • physical SIM card of docomo (5G): works

I have not tested connectivity of eSIM connection on KDDI. On Fairphone’s forum there is a report that eSIM of KDDI was not recognized on Fairphone 4, while /e/OS might recognize one. Connectivity of Softbank and Rakuten, the other two large mobile carriers, is not tested as well, but it might be worth for some tests.

After installation since several days I have not experienced a critical problem yet.

Here is the phone’s information:

Baseband version: MPSS.HI.2.5.1-01001-BITRA_GEN_PACK-1
Kernel version: 4.19.157-perf-g81c35c565a1b #1 Wed Jan 10 12:32:28 UTC 2024
Build number: e_FP4-user 12 SQ3A.220705.004 eng.root.20240110.121825 dev-keys

Hope this helps for those who would like to use Fairphone 4 in Japan.

Regain your privacy! Adopt /e/OS the unGoogled mobile OS and online servicesphone


I have updated the phone to 1.20.0-s, and it continues to connect to the mobile carriers.

When I came to Japan I giftec my FP3 to my japanese friend. He licked the concept of Fairphone. Since /e/OS was on it and he uses google, I installed stockon it for him. Can’t change ones mind. With one provider (au antenna but other company) he didn’t get a signal. He switched providers recently to NTT docomo and it also doesn’t work. I am sure I used a data sim with Softbank with that FP3 and e/OS/ 1.5 years ago.

Are you telling me Stock doesn’t work but e/OS/ does?

I do not know about FP3 as I have not tested it. What I am saying is that while stock OS on FP4 did not connect to the Japanese mobile carriers which I use, /e/OS did.

That is also my experience.

Never had issues with e/OS/ but I was always on a Softbank network😅

We should start a japanese community here :grin::grin:

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I updated /e/OS on FP4 to 2.0 the other day, and the phone continues to recognize the Japanese mobile carriers :+1: