Ruby script to import vCard "cell" type phone numbers to a roster: https://gist.github.com/singpolyma/e757d312ef8d4ef0da6a238163eed9cf
Python script to import from CardDAV: https://gitlab.com/djsumdog/dav-xmpp-sync
Lua script to import from khard vCard store: https://the-brannons.com/cgit/cgit.cgi/commtools/tree/README.md