This Technical Bulletin outlines mandatory requirements for the handling of Unique Reference Numbers (URNs) by NSI-approved companies, aimed at improving the efficiency and accuracy of ECHO call handling. Companies must ensure that URNs are accurately transmitted without modifications and incorporated into their documented processes, with full compliance expected by April 2025. Audits will assess adherence to these requirements, and while retroactive corrections of existing URN data are not required, it is recommended that companies review historical data for accuracy.