Think that is useful Kamailio enhancement. Here is example how use systemd activated sockets. [Example 1](https://github.com/apache/httpd/blob/969e885f2e8707ae7c5330ab24c626f7154e8f8...)
Then need to get received socket info and map to `listen` directive in kamailio config for advertised IP info. If no listen directive is provided, then one of option may be applied. 1) use socket as is, without advertised IP info; 2) generate error like "systemd activated sockets not match to listen directives in kamailio config file".