Sip Settings - Grandstream Networks GSC3505 Series User Manual

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
NAT
If the outbound proxy is configured and used, it can be set to "NAT NO".
Traversal
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
Proxy-
be supported by the proxy. Do not configure this parameter unless this feature is supported on the SIP
Require
server.

SIP Settings

SIP Basic
Settings
SIP
Allows the device to send SIP REGISTER messages to the proxy/server. The default setting is "Yes".
Registration
Controls whether to clear SIP user's information by sending un-register request to the proxy server.
When set to "All", the un-registration is performed by sending a REGISTER message with "Contact"
header set to * and Expires=0 parameters to the SIP server when the device starts pre-registration
Unregister
after rebooting.
before New
Registration
If set to "Instance", the device only cleans the current SIP user's info by sending REGISTER message
with "Contact" header set to concerned SIP user's info and Expires=0 parameters to the SIP server.
The default setting is "Instance".
Register
Configures the time period (in minutes) in which the device refreshes its registration with the specified
Expiration
registrar. The default setting is 60. The maximum value is 64800 (about 45 days).
(m)
Subscribe
Specifies the frequency (in minutes) in which the phone refreshes its subscription with the specified
Expiration
register. The maximum value is 64800 (about 45 days).
(m)