If your telco authenticates phone support using your government ID number, it very well may work. People in some countries do not even try to keep their ID numb

If your telco authenticates phone support using your government ID number, it very well may work. People in some countries do not even try to keep their ID number private. Some companies ask you to enter it in various places for their own convenience. It was the same in the US some years ago...people did not view SSNs as very sensitive personal data. Some of those people are still alive today.