The log containing `ssl3_read_bytes:sslv3` is not related to the protocol version itself, it's about internal functions inside libssl that are also used for tls. Besides the prefix, the log message is retrieved from the libssl, suggesting a possible issue with certificates or client application. It is before kamailio gets any traffic or control over the tls connection.
It is more about usage of kamailio and your client apps, i suggest you try to figure out what kind of clients end up in this case and troubleshoot further using higher debug level to get more verbosity in the syslog. Then discuss further on sr-users@lists.kamailio.org to get assistance from community. It doesn't look to be an issue in the code of kamailio.