This is an incredibly simple and small application that provides only the integrated circuit card identifier (ICC ID) of the current subscriber identity module (SIM) card. This number is needed when transferring from one network provider to another. It makes the transition much easier without the need to switch off the phone/tablet to get this value that they require.
To read more about the ICC ID, go to http://en.wikipedia.org/wiki/ICCID#ICCID.
Read phone state: this is required to get the value of the ICC ID.
And nothing else!