DAG1000/2000 Series FXS Voice Gateway User Manual37Note:* private services are open by default4.8.7 System ParameterSystem parameters include: STUN、NTP、Provision、WEB parameter、Telnet.1)STUN:STUN(Simple Traversal of UDP over NATs)is a network protocol. It allows users backof NAT find their own public network address, NAT type and internet end port have been boundby NAT for a local port. Two back of NAT router devices established UDP communicationthrough this information.STUN doesn’t support TCP connection and H.323.2)NTP:Network Time Protocol(NTP)is a computer time synchronization protocol.3)Provision:Auto Provisioning can be used to provide general and specific configurationparameters ("Settings") to the DAGs and to manage firmware actualization.System parameter configuration interface as follow:Figure 4.8-11System Configuration Interface