User`s manual

VoIP/(802.11g) ADSL2+ (VPN) Firewall Router
Chapter 4: Configuration
110
Advanced – Parameters
VoIP through IP Interface: Select where to send/receive the voip traffic, either ipwan or iplan.
If the location of the SIP server is in the Internet then select ipwan. (Default)
If the VoIP SIP server is on the local Network then select
iplan.
Voice Frame Size:
Frame size is available from 10mSec to 60mSec. Frame size means how many
milliseconds the Voice packets will be queued and sent out. It is ideal to have the same frame size in both
Caller and Receiver. Default is 20mSec
PSTN Auto-fallback: Whenever a VoIP SIP response error code is received matching the codes in the
Edit section, the VoiP calls will automatically fallback to PSTN. The call will be sent via the PSTN when
VoIP SIP returns a specified error code.
Click the Edit to add or remove the response code. Ensure the codes are separated by a comma (,).
For more information about SIP response codes, please check to link to:
http://voip-info.org/wiki/view/sip+response+codes
NOTE: PSTN Auto-fallback is not applicable in Australia and should not be enabled.
T.38 Fax Relay: Allows the transfer of facsimile documents in real-time between two standard Group 3
facsimile terminals over the Internet or other networks using IP protocols. It will only function when both
sites are enabled to support this feature.