The easiest way how to achieve VCF to SNN conversion is to import your contacts from the *.vcf file to your phone using the Samsung Kies and then perform a backup procedure that generates the SSN file.
Convert vCard contacts to Samsung Kies notes backup file.
We found 2 software records in the database related to .vcf to .ssn file format conversion.
Microsoft Windows software - convert vcf to ssn on Windows
A free software for managing of latest Samsung mobile devices
Convert from vcf file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned vcf to ssn. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert vcf to ssn on OS X
Management and sync utility for Samsung mobile devices