International Subscriber Identity Modules (more commonly known as International SIM Cards) are used in GSM subscriber modules. Universal SIM cards provide a secure way to store IMSI service subscriber keys for mobile cellular devices, and have the additional capability of not being device specific so they are able to be removed from one 

mobile phone and the Sim card inserted into another mobile phone.  Mobile Phone sim cards are mandatory for all GSM mobile phones, and the benefits of the WorldSim Sim card is that it is able to function in most countries of the world, whereas as other commercially available Sim cards are only able to function locally.

The current Global Sim Card has the width of 25mm, a height of 15mm and a thickness of 0.76mm. WolrdSim global sim cards (Universal Sim Cards) come with two main operating system types (Native or Javacard). Native SIMs are based on vendor specific software whereas Java Card SIMs are based upon Java Programming Language.

When using the internationally Global Sim Card, the SIM which stores the network state information is able to broadcast to the hand held device. This facility enables the mobile device to have roaming capabilities, so when the mobile changes from one location area to the next, it can store its unique LAI number for the new location.