When it comes to “SIM cards”, it is often difficult to know what it
really refers to. This page aims at summing up the realities behind the
“SIM cards” designation.
SIM (Subscriber Identity Module)
is an integrated circuit which securely stores the service-subscriber
key (IMSI) to identify a subscriber on mobile telephone device. The
SIM is a removable card which can be transferred from one device to
What is a micro-SIM?
A micro-SIM card has the same thickness as the SIM card but their
length and width reduced to 25 mm x 15 mm. Micro SIM cards are
currently used in many of the new generation smartphones.