To make things easier, we'll assume Bounded Contexts have a Customer - Supplier relationship.
With modern RPC, we refer to RPC through RESTful resources. A Bounded Context reveals a clear interface to interact with to the outside world. It exposes resources that could be manipulated through HTTP verbs. We could say that the Bounded Context offers a set of services and operations. In strategical terms, this is what is called an Open Host Service.
Note
Open Host Service
Define a protocol that gives access to your subsystem as a set of SERVICES. Open the protocol so that all who need to integrate with you can use it. Enhance and expand the protocol to handle new integration requirements, except when a single team has idiosyncratic needs. Then, use a one-off translator to augment the protocol for that special case so that the shared protocol can stay simple and coherent. Eric Evans - Domain-Driven Design: Tackling Complexity in the Heart of Software...