What is STUN?
Simple Traversal of UDP over NAT (STUN) ? is a protocol that enables a VoIP device, such as the DVG-2001S or an IP phone, to detect the presence and type of NAT behind which the phone is placed. The DVG-2001S supports STUN and can intelligently modify the private IP address and port in its SIP/SDP message by using the NAT mapped public IP address and port through a series of STUN queries against a STUN server located on the public Internet. This will allow SIP signalling and RTP media to successfully traverse a NAT without requiring any configuration changes on the NAT.
Below is a list of Public STUN servers
- stun.fwd.org (no DNS SRV record)
- stun01.sipphone.com (no DNS SRV record)
- stun.softjoys.com (no DNS SRV record)
- stun.voipbuster.com (no DNS SRV record)
- stun.voxgratia.org (no DNS SRV record)
- stunserver.org see their usage policy