What is a SIM card?

Mobile phone and SIM card together constitute mobile communication terminal equipment. Whether GSM or CDMA systems, digital mobile phone users in the "network" will be a SIM card (subscriberidentitymodule) or Uim card (useridentity Module). SIM card is a GSM compliant "smart card" can be inserted into any GSM-compliant mobile phone, to achieve "phone number with the card is not random function," and the call cost automatically credited to the card users of the bill, and the phone is irrelevant.

External features

There are two SIM cards with the same functionality and different forms in the actual use:

Card-type (commonly known as KCAL) SIM card, this form of SIM card in line with the relevant IC card ISO7816 standard, similar to IC card.

Embedded (commonly known as small card) SIM card, its size is only 25mmx15mm, is semi-permanent loaded into the mobile device card.

"Kcal" on the real effect is it on the "small card", and "small card" on the part of the card on the surface of the copper interface and its internal seal logic circuit inside the card. The current domestic popular style is "small card", small card can also be replaced by "kcal" (need to install a Cato). "Kcal" and "small card" are applicable to different types of GSM mobile phones, early models such as Motorola Gc87c, 308C and other mobile phones are "kcal", and the current new models are basically using "small card."