I know you are planning to use SN to CTB. If you survive they will ask how you got poisoned, if you don't tell them your real intention they will never know what your real intentions were.
However if you use other methods to ctb, methods that are more obvious like hanging they will they will certainly know you tried tried to kill yourself.
The first thing they will do is a psychiatrist evaluation, if they think you should go to a psych ward, they will tell you. If you refuse to go they can consider a Compulsory Health Treatment ( TSO in Italian).
During the treatment contact with the outside world will be severely limited. Asking your question, they can't go over your phone, it would be illegal.