For anyone who does not know the card can be used anywhere Discover is accepted.
If JCB can be used anywhere where Discover is accepted, can Discover be used anywhere JCB is accepted?
Correction, it can only be used at US retail store where Discover is accepted.
JCB-Discover alliance only covers retail acceptance (no mail order or online shopping), and only covers US portion.
JCB can be used on Amazon..... Isn't that "online"?
That is because Amazon explicitly says they take JCB.
In cases where one website takes Discover but makes no mention of JCB, JCB cannot be used. daybreakgonesXe sumed it up.