dear aspirant,

The date of issue of call letter will be announced soon.

Shortlisted candidates will be informed about their selection for SSB interview on their E-mail or through SMS. Eligible candidates will be able to download their Admit Card/ Call Letter of Indian Navy 10+2 Cadet B.Tech Entry for Interview as soon as available on the official website. 

good luck

Hii aspirant ,
Coming to your question the call letter for the SAB interview for the 10+2 btech entry scheme in the Indian Navy will be available once the registration process gets closed that is after the 17 June but in this year only , generally the dates for the SsB interview for this entry is between October or November .
For the SSB You will be get notified in your registered email id that is the date of your SSB interview your reporting time and your centre for the SSB interview .

Hope this helps you if you still have any doubt regarding this feel free to ask .
Good luck :)