Do you have an NSCC interface?
We have built out the NSCC interface (Fund/SRV interface), and it is fully unit tested.  Unfortunately, the NSCC does not allow for a full integrated test environment without an actual fund family to test with.  Our engineering staff has been through the integration testing phase with the NSCC before, and we have a working relationship with the person at the NSCC responsible for testing interfaces, and have worked with them before, going through the testing process.