The diagram below shows the final payment instruction process. The Source Bank will be aware that something has gone wrong if either Message 4 or Message 15 are not received, and can then trigger an investigation.
Investigations always needs to be sent to Nexus, as the Source IPS only has a partial view and does not know what happened at the Destination IPS.
If Message 4 is not received:
The Source Bank does not have clarity about the status of payment processing in Source country via Source IPS. This could be due to a failure in processing within Source IPS, or a connectivity problem between the Source IPS and Source Bank).
The Source Bank should send the investigation message directly to the Nexus Gateway. The Nexus Gateway will reply, potentially after an investigation at the Source IPS.
If Message 15 is not received:
Multiple possible points of failure in Source or Destination Gateway, Destination IPS or connectivity between the different systems.
Source Bank initiates an inquiry message with the Source Gateway
Source Gateway checks if it is aware of the status and if so, sends the status
If not aware, Nexus Gateway forwards the inquiry to Destination Gateway
Destination Gateway checks if it is aware of the status and if so, sends the status
Otherwise, Destination Gateway forwards the investigation message to Destination IPS and processes the response
ISO 20022 Equivalent messages
The messages between the banks and the IPS are based on the local standards. The messages between the Nexus Gateways are based on the ISO20022 standard, where: