Next, use the "ast_tls_cert" script in the "contrib/scripts" Asterisk source directory to make a self-signed certificate authority and an Asterisk certificate.
./ast_tls_cert -C Your_Domain -O "Your Name" -d /etc/asterisk/certkey
Enter pass phrase for /etc/asterisk/certkey/ca.key:Your_Password
./ast_tls_cert -m client -c /etc/asterisk/certkey/ca.crt -k /etc/asterisk/certkey/ca.key -C Your_Domain -O "Your_Name" -d /etc/asterisk/certkey -o YourSIPClient
chmod -R -f 755 cert/