Becoming a free supporter of Rakuten Mobile, I am on my first overseas business trip. I visited San Francisco, where the Samsung Electronics recital was held. As a line for the interview, I tried roaming using a SIM card from Rakuten Mobile. Roaming fee is 0 yen during free supporter period. The capacity is tentatively limited to 100GB, but it can be said that it is virtually unlimited because it can be replaced.
I tried international roaming with Rakuten Mobile SIM card
First, let's review the basics. Rakuten Roaming's international roaming scheme is very different from the three major carriers. Rakuten Mobile connects to overseas carriers via Orange, a French carrier, while the three major carriers each provide roaming services by directly connecting to local carriers. To be more precise, it is better to say that the SIM card will be switched to Orange only when traveling abroad.
As a mechanism, we have two IMSIs with unique identification numbers assigned to SIM cards, and use them according to the country or region where they are used. Of course, not just the service of Orange, but also the ultimately transmitted information to the network of Rakuten mobile side, the used capacity is counted. By switching the contents of the SIM card, the roaming route was via Orange.
▲ Orange services are used for international roaming. IMSI of two carriers can be stored in one SIM card and can be switched and used
Try with a device not covered by the support program
This time, I decided to use the SIM card in the docomo version "Galaxy Note10 +". However, even if I get off at the airport and turn on the power, I do not grasp the network at all. It may not be helped because it is not a target model of the free supporter program, but it seems that IMSI is still Rakuten Mobile.
Okay, I reinserted the SIM card into OPPO's "A5 2020" purchased for the free supporter program and turned it on. After a while, I connected to AT & T, a US carrier. However, APN remains "rakuten.jp" for Rakuten Mobile. At first glance, I don't know if the IMSI has switched. However, when I tried a speed test as a test, the connection path was via Orange.
▲ When I pointed SIM to OPPO A5 2020, roaming was performed immediately
▲ The APN was connected as it was at Rakuten.jp, but the MMC showing the carrier name was that of Orange
Why did the Docomo version Galaxy Note10 + fail, and if it was OPPO A5 2020, it immediately switched to Orange. This is probably due to the elimination of an application for rewriting SIM card information called "SIM Toolkit" from the docomo version of the terminal. Actually, after starting international roaming in A5 2020, I re-inserted the SIM card in Galaxy Note 10 + again, and I was able to communicate similarly.
When I opened the APN column of Galaxy Note 10+ again, the APN column was filled with Orange APN. When communication was not possible, it was Rakuten Mobile's APN, so you can see that IMSI switched to recognize it as an Orange SIM card. We use it from late afternoon to night when we arrived in this state, but there were no particular problems.
▲ When you insert a SIM card after roaming is possible, Orange APN appears. This is also because the SIM card IMSI has been switched
By the way, in the United States it seems to be connected to either AT & T or T-Mobile. We did a network search and were able to connect these two, and we didn't connect to the remaining two carriers, Verizon and Sprint. In the city of San Francisco, honestly, it is enough to connect either way, but unless you are out of the suburbs or in a metropolitan area, my experience seems to be more convenient to connect to AT & T.
▲ Although detailed information has not been released from the Rakuten Mobile side, it seems to be connected to AT & T and T-Mobile in the United States
The communication speed is slightly lower than 10Mbps at a hotel in the center of San Francisco. It may not be suitable for downloading large files, but it is fast enough to browse the web and download relatively small photos. The bottleneck is that the delay is over 500ms due to roaming, but this is a point that it can not be helped because it is not directly connected to the local carrier.
▲ The speed was measured by AT & T. The delay is a bit worrisome, but the speed is reasonable
Since it was a relatively short time from the declaration of entry to the launch of the service, roaming like three major carriers would have been difficult. Negotiating with each company requires manpower. Switching the entire IMSI of a SIM card in that sense may be a tricky solution like Rakuten Mobile in that sense.
While roaming, you couldn't use phone or SMS, but Rakuten Link has made it possible. The use of the latest standard RCS [Rich Communication Service] to supplement missing services is also a new entrant, and it gives a good feeling.
▲ I can't make calls, but I could make and receive calls via Rakuten Link
On the other hand, this method has its limitations. This time, the terminal is limited as my docomo version Galaxy Note10 + was not available at first. Because the terminal is specified during the free supporter program, the author who used the docomo version Galaxy Note 10 + is bad, but if this service accepts another terminal, trouble may occur.
In fact, if you move from DOCOMO as it is, there will be no way to deal with it. If you try to use a phone or SMS, Rakuten Link may become a must, and at this time iPhone will be out of your choice.
At the moment it's free, so I don't mind any trouble, but it's unclear how much it will cost. For international roaming of carriers, docomo and au issued 980 yen for 24 hours, but docomo has a multi-day contract, au has introduced a mechanism to receive discounts with advance reservations, and price competition is occurring. It is worth noting how far you can compete here.