The present document describes the extensions required for the support of the Generic Addressing and Transport
protocol (GAT) mechanism over the public Network Nodal Interface (NNI). This application makes use of the
Application Transport Mechanism (APM) described in EN 301 069-1 (V1.3.1) [1] for bearer related signalling, and the
Transaction Capability (TC) for signalling involving no bearer. The present document specifies the respective users
(i.e. APM-user, TC-user) to support signalling applications using the Generic Addressing and Transport protocol as
defined in EN 301 813-1 [2] (ITU-T Recommendation Q.860, modified).