DAG1000/2000 Series FXS Voice Gateway User Manual515. Glossary• DNS：Domain Name System• SIP：Session Initiation Protocol• TCP：Transmission Control Protocol• UDP：User Datagram Protocol• RTP：Real Time Protocol• PPPOE ：point-to-point protocol over Ethernet• VLAN ：Virtual Local Area Network• ARP：Address Resolution Protocol• CID：Caller Identity• DND ：Do NOT Disturb• DTMF ：Dual Tone Multi Frequency• NTP：Network Time Protocol• DMZ：Demilitarized Zone• STUN ：Simple Traversal of UDP over NAT• PSTN ：Public Switched Telephone Network
