What do u mean by 19 digit of SIM Number?

19 digit number Is a serial number

It SIM ICCID Number (ICCID = IC Card ID)

- digit1 -2 = GSM number

- digit3 -5 = Country Code

- digit6 -7 = Network Code

- the rest are manageable SIM number

Sim=subscriber i dentity module , which is a integrated electronic circuit which works on low power,

 19 digits of sim number is for identification of sim

for example xx xx xx xxxx xx xxxxxx x(19) 

the first two digits refers to the Telecom Id

then next two digits refers to the country code

then next two digits refers to the network code

then next four digits refers to the month and year of manufacturing

then next two digits refers to the switch configuration code

then next six digits refers to the SIM number

then last digit which is separated from the rest is called the “check digit”