The present document defines the security architecture of NGN Release 1. The definition complies with the requirements of ITU-T Recommendation I.130 [32] at stage 2. The present document addresses the security architecture required to fulfil the NGN R1 security requirements defined in [1] and includes the definition of security architectures to provide protection for each of the NGN functional architecture ([3]) and its subsystems ([6]@ [4]@ [27]@ [26] and [5]). Where appropriate the present document endorses security mechanisms defined in other specifications. This document addresses the security issues of the NGN core network and the NGN access network(s) up to and including the NGN Network Termination (NGN NT) in the residential customer domain. The NGN NT denotes a logical demarcation point between the residential customer domain and the NGN core and access networks and covers the corresponding interfaces.