Please allow mt to add more info about mail settings.
I use Softbank android smart phone.
To get SMS from oversea, following setting is needed.
Launch "My Softbank+" on desktop -> Tap "My page"(login is needed) -> "Mail Setting"
-> "Configure"(SMS/MMS) -> "Change" at Mail blocking configuration -> "Customize"
You can see the configuration of SMS from countries except Japan and select "yes".
I hope it will be help.