The NENA Call Blocking Information Document is intended to provide guidance to PSAP Administrators regarding what conditions should be required for a PSAP to identify a calling number as a problem source and develop a draft policy for having that source blocked. This document will also provide guidance on how to determine if the problem is resolved and the criteria to un-block the number. This document focuses on threats from individual sources; it does not address Distributed Denial of Service (DDoS) attacks where large numbers of individual sources are coordinated to simultaneously launch attacks.
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