RPC adumbrates the intricacies of the network by using the ordinary procedure call mechanism familiar to each programmer. A client process calls a function on a remote server and suspends itself upto it gets back the results. Parameters are passed like in any ordinary processes. The RPC, like ordinary processes, is synchronous. The process that issues the call waits upto it gets the results.
Under the covers, the RPC run-time software collects values for the parameters, forms a message, and sends it to the remote server. The server receives the request, unpacks the parameters, calls the processes, and sends the reply back to the client. It is a telephone-like metaphor.