I have a telecom card number that has been leaked! People can text me without knowing my card number.

It is normal. If you register anything with your mobile phone number, others can know your information. Your information is likely to be used for transactions on your registered platform.

Of course, it is also possible that the original owner of this mobile phone number was once known by many people, which led you to receive it.

In short, unless your mobile phone number has never been used by others before and has never been registered, it is impossible for others except the operator and your friends to know your number.