User's Manual
FIRMWARE VERSION 1.0.7.6    HT502 USER MANUAL     Page 31 of 48  
TABLE 9: ADVANCED SETTINGS 
Admin Password 
This contains the password to access the Advanced Web Configuration page. This field is 
case sensitive. Only the administrator can configure the “Advanced Settings” page. 
Password field is purposely left blank for security reasons after clicking update and saved. 
The maximum password length is 25 characters. 
Layer 3 QoS 
This field defines the layer 3 QoS parameter which can be the value used for IP 
Precedence or Diff-Serv or MPLS. Default value is 12. 
Layer 2 QoS  Value used for layer 2 VLAN tag. Default setting is blank. 
STUN Server 
IP address or Domain name of the STUN server. 
Keep-alive interval 
This parameter specifies how often the HT502 sends a blank UDP packet to the SIP 
server in order to keep the “hole” on the NAT open. Default is 20 seconds. Minimum 
value is 20 seconds. 
Use STUN to detect 
network connectivity 
Use STUN keep-alive to detect WAN side network problems. If keep-alive request does 
not yield any response for configured number of times, the device will restart the TCP/IP 
stack. If the STUN server does not respond when the device boots up, the feature is 
disabled. 
Firmware Upgrade 
and Provisioning 
Enables HT502 to download firmware or configuration file through either the TFTP, HTTP
or HTTPS server. 
Via TFTP Server 
This is the IP address of the configured TFTP server. If selected and it is non-zero or not 
blank, the HT502 retrieves the new configuration file or new code image from the 
specified TFTP server at boot time. After 5 attempts, the system will timeout and will start 
the boot process using the existing code image in the Flash memory. If a TFTP server is 
configured and a new code image is retrieved, the new downloaded image is saved into 
the Flash memory. 
Note: Please do NOT interrupt the TFTP upgrade process (especially the power supply) 
as this will damage the device. Depending on the local network, this process can take up 
to 15 or 20 minutes. 
Via HTTP / HTTPS 
Server 
The URL for the HTTP/HTTPS server used for firmware upgrade and configuration via 
HTTP.  
For example, http://provisioning.mycompany.com:6688/Grandstream/1.0.0.67“:6688” is 
the specific TCP port where the HTTP or HTTPS server is listening; it can be omitted if 
using default port 80. 
Note: If Auto Upgrade is set to No, HT502 will only do HTTP/HTTPS download once at 
boot up. 










