I'm not sure what you mean. When I think of External / Internal in this context I think of External web service calls that go out to another system. Conversely, Internal web service calls can be leveraged inside of ISM to essentially call a custom script to be run on a record inside ISM. Is that what you mean? Wouldn't the record updates gathered and placed into the ISM system records from the external calls be able to trigger the internal calls as needed also?