Synch call to split in synch and asych

Hi Guys,

we got a new request to split a synchronous interface to asynchronous and synchronous realtime.

SENDER (Service Interface Synchronous Outbound )              > SYSTEM A  (Service Interface Synchronous Inbound

                                                                                          >  SYSTEM B (Service Interface Asynchronous Inbound)

How can we handle this without BPM? Thank you.

PM