There are two ID numbers. The first is a National ID Number (NIN). This is a 12 digit number with the first 3 numbers showing the citizenship of the person with the remaining 9 numbers being unique to the person in question. The second is a Government Issuance Number (GIN). The GIN is a 16 digit number which is used within the government and should never be given to anyone with the exception of certain government offices.
The NIN is a publicly displayed number. It is the One Care ID number, the telephone number, the postal address (in some instances), the bank deposit number, and can be used in other instances. This will mean that knowing just the NIN will not be likely to do any harm such as identity fraud. With foreign nationals, the first three digits of the NIN will be the same with all of the nationals of a particular country. For example, all United Kingdom nationals will start with 854, but all US nationals will have their NIN start with 872.
As mentioned, the GIN is a 16 digit number that should never be given out with ease. No government authority will call or email requiring the GIN. Therefore, if such claims to be from the government, make note of the incoming number, and report it to HHS. The only time one should give out the GIN is if they go to an HHS building, call 711 or visit a .gov.ka site. For identity verification, the company requiring verification will give you their NIN, and that would be used to generate an identity number by going through the HHS. This number will not be related to the GIN, but will prove to the company that you are whom you say you are. This is obviously a little more work, but intended and designed to reduce or eliminate identity theft or identity fraud,