Grandstream Networks GSC35 Series User Manual page 37

NAT Traversal
Proxy-Require
On this mode, the device will resolve DNS SRV records and tries to send
the request to the server having lowest priority and if it doesn't respond, it
will move on to the next IP until one of the servers responds, once this
happen the device will keep contacting this responding IP until DNS
timeout (30 minutes) before starting over.
• Saved one until no response (Stay on responding IP until its
failure):
On this mode, the device will send SIP requests to the last responding IP,
and it doesn't failover/switchover to the next one until this responding
server is down.
Specifies which NAT traversal mechanism will be enabled on the device.
It can be selected from the dropdown list:
•
NAT NO
•
STUN
•
Keep-alive
•
UPnP
•
Auto
•
OpenVPN
If the outbound proxy is configured and used, it can be set to "NAT NO".
If set to "STUN" and STUN server is configured, the device will periodically
send STUN message to the SUTN server to get the public IP address of
its NAT environment and keep the NAT port open. STUN will not work if
the NAT is symmetric type.
If set to "Keep-alive", the device will send the STUN packets to maintain
the connection that is first established during registration of the device. The
"Keep-alive" packets will fool the NAT device into keeping the connection
open and this allows the host server to send SIP requests directly to the
registered phone.
If it needs to use OpenVPN to connect host server, it needs to set it to
"VPN". If the firewall and the SIP device behind the firewall are both able
to use UPNP, it can be set to "UPNP". The both parties will negotiate to
use which port to allow SIP through. The default setting is "Keep-alive".
Adds the Proxy-Required header in the SIP message. It is used to indicate
proxy-sensitive features that must be supported by the proxy. Do not
configure this parameter unless this feature is supported on the SIP server.
GSC35XX Series User Manual
Version 1.0.0.15
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