Using in Japan


    I have the T-Mobile ONE Unlimited 55 plan on an iPhone 6 (soon to be iPhone8) .  I have two questions for use in Japan.  (1) what's the call charge for Japan-to-Japan calls?  and (2) what is the plan's ata speed in Japan, and if I want to increase data speed, what data speed does the $10/month add on get, and what data speed does the $25/month plan get?

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