Sim cards

hi,
i know this topic is covered extensively in the forum but i've searched through the previous threads and none of them seem to answer my question specifically. So, sorry if i missed something!
If you buy an unlocked Softbank phone, that is supported by your local service provider (GSM and WCDMA/3G etc) then what SIM card do you use?can you even get one, since its clear that japanese phones don't usually accept foreign countries' SIM cards? The person i'm considering buying this phone from has been using the phone in america,so how is that possible? thank you to any help!

SO WE DO NOT KNOW.MAYBE 0.5% OF CELL FONE USER USES THAT.

An unlocked Softbank phone sounds suspect to me. Phones in Japan don't typically use SIM cards so I would be surprised if it works. The biggest problem is that Japanese phones are designed at a hardware level to work with specific Japanese companies and are not meant to work on other networks. The result is that if you do get it to work, all the features that would make it interesting would like not function. Also note that someone using a Japanese phone in the US on a Japanese Service plan is completely different than using a Japanese phone in the US on a US service plan.

See this page for more info on phones in Japan.

http://www.japan-guide.com/e/e2223_top.html