ATIS 1000074-E

This Errata contains an update to ATIS-1000074 and defines the framework for telephone service providers to create signatures in Session Initiation Protocol (SIP) and validate initiators of signatures. It defines the various classes of signers and how the verification of a signature can be used toward the mitigation and identification of illegitimate use of national telecommunications infrastructure and to protect its users. The original ATIS-1000074 is included with this product.