Hii Utkarsh ,
Coming to your question as you had registered for the Indian Navy 10+2 btech entry scheme you will be shortlisted and if you names will get into it the you have to go for the ssb interview process  which is a 5 day interview process and if you got selected in it then you will go for the medicals thereafter only and if this all hurdles is passed by you than you will be getting the call letter for the Indian Navy, basically for this entry the call letter is given in the month of the December as joining is to be done in the January.

Hope you are now clear about your call letter issues, feel free to ask if you still had doubt.
Good luck buddy.