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VoIP/(802.11g) ADSL2+ (VPN) Firewall Router
Advanced – Parameters
VoIP through IP Interface: IP Interface decides where to send/receive the voip traffic; it includes: ipwan
and iplan. Easy way to select the interface is to check the location of the SIP server. If it locates some
where in the Internet then select ipwan. If the VoIP SIP server is on the local Network then select iplan.
Voice Frame Size: Frame size is available from 10ms to 60ms. Frame size meaning how many
milliseconds the Voice packets will be queued and sent out. It is ideal to have the same frame size in
both of Caller and Receiver.
PSTN Auto-fallback: Whenever VoIP SIP responses error and error code matching with the codes in the
Edit section, the VoiP calls will automatically fallback to PSTN. In the other word, the call will be called
via the PSTN when VoIP SIP returns an error code.
Click the Edit to add or remove the responses code. To be sure the code is separated by a comma (,).
For
more
information
about
SIP
responses
codes,
please
check
to
link
to
http://voip-info.org/wiki/view/sip+response+codes
where you can get to know the meaning of each error
code.
T.38 Fax Relay: It 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 support this feature and enabled.
Advanced – PSTN Environment Adjustment
PSTN Environment Adjustment options will help you to adjust the onhook and offhook voltage detection
values for your environment. You should use these if the default values are incorrect and result in PSTN
calls not being detected properly, e.g. calls being terminated within 5 seconds of being answered. The
actual levels are determined by your environment including the number and type of telephones used.
Note: ONHOOK means hung up.
To take your phone OFFHOOK, lift the receiver then press Hook/Flash until you hear your normal PSTN
dialtone, not your VoIP dialtone. Wait several seconds and then press Check Level.
You should check the OFFHOOK value for each telephone you have connected to this device. Set the
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Chapter 4: Configuration
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