I recently took a two week trip to the U.S. After searching around for different data plans to use with my SIM-free iPhone 7 Plus, it turns out the best plan didn’t require a SIM-free phone at all. I have a contract with Softbank, one of the “big three” mobile carriers in Japan. And Softbank currently lets people with smartphone contracts use their phones completely free while traveling in the U.S. That is free talk to calls made in the U.S., free calls made to and from Japan and, best of all, unlimited data, including tethering. The plan is called “America Houdai” (America Unlimited). No extra contract is required. Just follow their simple settings procedures for leaving Japan and arriving in the U.S. and it just works.

Here are the Pros and Cons of my two week experience using America Houdai in Boston. I waited to write this report until after my bill for April was finalized just to make sure there was no “funny stuff” about the plan.

Pros

• It is free if you have a SoftBank contract and a supported smartphone, which are most smartphones. It doesn’t matter if your phone is SIM-free or locked to Softbank.
• Data is truly unlimited. I called and confirmed this any number of times and it really, truly did turn out to be unlimited data, including tethering. I used over 25 GB of data in my two weeks (even with TripMode on my Mac to keep unnecessary background data at a minimum) and there were no slowdowns.
• The data speeds were not bad for a cell phone in the U.S. In my sister’s Brookline apartment I would regularly get 10-20 Mbps speed. Of course that doesn’t compare to what I get in Japan, but you can definitely get your work done at those speeds.
• You can make unlimited calls out to U.S. numbers and you can make and receive unlimited calls to and from Japan. People in Japan call you as usual, and they don’t even realize they are calling the U.S.

Cons

• You don’t get a U.S. phone number. There doesn’t seem to be a risk of somebody seeing your caller ID and accidentally returning a call from within the U.S. (which would be an international call to Japan for them) because your entire Japan phone number isn’t sent. Still, people in the U.S. don’t really have a reasonable way of calling you. I suggest getting a Skype-in number and using Skype for calls instead.
• Voice calls tend not to be very clear.
• Oftentimes,  calls will simply not connect. Any number of times I got an “unable to complete your call at this time” recording. But the problem was with Softbank/Sprint and America Houdai and not with the number I was calling, because whenever that happened I was able to call using my Skype account on my iPhone instead.
• Data seems to originate from Japan, even though you are on the Sprint network. For example, I wanted to watch Hulu one evening and Hulu thought I was in Japan, so I needed to connect via a VPN instead (like I do when I am actually in Japan).

Other

• Even though I had data roaming turning off (one of the procedures you are supposed to check) somehow roaming data slowly accumulated over the two weeks, reaching about 2 MB in all. I was concerned when I saw that happening and called Softbank while in the U.S. and they said they would make a note of it. This ended up being reflected in an extra 676 yen charge on my latest Softbank bill. I called them today and they said they would refund the 676 yen from my next month’s bill. So despite it being free, and despite following all the settings, you should still check your bill for minor charges cropping up and call Softbank when you get back to Japan if there is a problem. If you see roaming data inching up over your trip, I also recommend calling Softbank and mentioning it to get it on the record. You will get plenty of daily messages from Softbank letting you know you are connected to the Sprint network and in those messages there is a 24-hour phone number to call if you are having issues.

Conclusion

America Houdai is absolutely worth it even for the data alone. There are no U.S. data plans from AT&T or other companies which will give you 25 GB data for two weeks at a reasonable price, much less free! But you do need Skype or some other way to really feel comfortable about making and receiving phone calls, and the voice calls are definitely not very clear.

Still, overall, America Houdai was extremely useful to me on my trip. And you can’t beat the price!

If you travel back and forth to the U.S. a lot I think it’s probably a good reason to use Softbank as your carrier.