As we know, WS bindings are local-optimized as long as the Server URL configuration for your soa-infra matches your invoked endpoint. To check if local optimization is actually kicking in, you can wither
a) Chek your HTTP access log to see if calls are going over HTTP.
b) Set the the logger for oracle.integration.platform.blocks.soap.WebServiceExternalBindingComponent to FINE (TRACE:32). If local optimization is kicking in, you should be able to see logging messages such as "Invoking service request locally..." in your log files.