Originally Posted by billatq

Technically what I said is slightly inaccurate, since my reply was geared towards people trying to use it on websites for manufactured spend. JCB in the US is processed on the back-end using Discover, but it's not generally on, and it almost never works for websites as Discover because the bin numbers are filtered.

You can test JCB on authorize.net using the number here: http://developer.authorize.net/testingfaqs/