NetScreen Gatekeeper Protocol (NSGP) is a Juniper Networks proprietary peer-to-peer protocol that enables a security device to act as a server for voice-over-IP (VoIP) traffic. NSGP is used to prevent overbilling attacks that can occur when using the GPRS tunneling protocol (GTP) for VoIP. It is not supported on SRX.
SRX does not support NSPG. There is no schedule to support it yet.