Integration

As OSB is the strategic ESB and is used for external services does it make sense that all communication must go out via the OSB.
For example if I have a request that comes in gets routed through the OSB and then calls a backend composite which contains a BPEL that sits on the Oracle SOA server that calls multiple external services (CRM, SAP etc..) Would all the calls out from the BPEL then go back to the OSB and out to the external services (via proxy/business services.) This seems to add a lot of network hops to the whole architecture.
I can't really seem to find a diagram to explain this but an external service consumer could call the Oracle SOA stack that will come in via the OSB (for security gateway as OWSM 11g doesn't support gateway yet.) Then get transformed into the CDM and then passed on to the Oracle SOA server that has a composite service with BPEL that orchestrates multiple calls to internal and external services. The external ones requiring a transformation back into the service providers format.
How does this flow work?