Smart-cards, SIM cards and Java Card are all at the center of mobile, directly or indirectly. It is at the center of your daily mobile handset use (the SIM card), on mobile payments, the future of contact-less applications, and all kinds of mobile commerce applications. SIM cards and Java Card are here to stay. So it is good to be familiar with SIM-cards, Smart-cards and Java Card in general:

SIM Card Overview

Java Cards and Secure Elements

Java Card 3

Smartcard Web Server


Some Good External Resources