This issue came about in the following way. When it was first released in January, in addition to the so called "LTE Band 3" of wavelengths that Rakuten Mobile operates themselves, the Rakuten Mini was able to utilize the "LTE Band 1" that the three main phone carriers posses. The versions that Rakuten sold in May were changed twice and by the third version, "Band 1" was removed as a band it could utilize. They did not change their published technical specifications nor did they announce it to users.
With regards to the change, Rakuten Mobile says this was due to device limitations. This is because the initial version of the Rakuten Mini did not have the wavelengths to support communications in North America and when they tried to add the bands, they had no choice but to remove Band 1.The fear of being unable to get signal
The law requires that most devices that emit radio waves such as smartphones must acquire the so-called "Giteki" (The Technical Standards Conformity Approval based on the Telecommunications Business Act and the Technical Standards Conformity Certification based on the Radio Law are both part of this) certification from The Ministry of Internal Affairs and Communications as a countermeasure for jamming and other interference. The Ministry finds the fact that the Rakuten Mini is utilizing its original Giteki despite the fact that it has changed its bands to be a problem.
Through a report to The Ministry of Internal Affairs and Communications, it was also discovered that the initial version released in January displayed the certification information of after the bands were changed. This was also found not to fulfill the standards of the Giteki. Of the three versions of the Rakuten Mini, only the second version had the correct certifications.
As a suspected violation of the rules governing the usage of radio waves, this is not simply a problem with the paperwork. Because Rakuten Mobile sold the Rakuten Mini as an unlocked smartphone, there is the risk that it caused damages for certain users.
The Rakuten Mini uses an internal eSIM chip to write certification data. This for example allows one to use the discount carrier IIJ, which is an eSIM service. IIJ borrows NTT Docomo's infrastructure to conduct their business and Docomo uses Band 1 as the basis for their service coverage across Japan. For customers who want to switch to IIJ's eSIM when outside Rakuten Mobile's service area or customers who only bought the phone itself and want to use IIJ, a Rakuten Mini that is unable to use Band 1 has the risk of immensely decreasing the size of the coverage area for customers.Rakuten's service area is still limited
Rakuten Mobile says that the reason they changed the bands was to make it more convenient to use it in North America. And indeed, the latest version which does not have Band 1 is able to utilize the main bands of North American telecommunication providers. However, Band 1 is also used in North America and the Asia-Pacific region as an auxiliary band by telecommunication providers. As it currently is, if one goes to certain regions, there is the risk of the coverage area decreasing in size and being unable to reach certain speeds.
Because they did not tell users when they changed their bands, Rakuten Mobile is allowing people who wish to to change their version to an older version. They also have reacquired the Giteki certification and with a software update now display the correct Giteki Mark on the screen.
However, it is highly unusual to change the bands of a smartphone after it has been released especially without changing the published technical specifications. The fact that the bands the device is able to use was changed repeatedly makes it clear that there are internal issues inside the corporation.
Rakuten Mobile reached 1 million applicants for their service at the end of June, which was faster than they had planned. They have a successful campaign in which the base monthly fee of 2980 yen is waived for the first 3 million applicants. On the other hand because their own coverage area is still very limited, issues such as connectivity problems were brought to the fore immediately after the service was started. In order to not decrease the pace at which they are gaining customers, it appears that they need to dispel the distrust customers have of their service.
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