User`s manual

Version 5.4 87 May 2008
SIP User's Manual 3. Web-Based Management
Parameter Description
Fax/Modem Bypass
Coder Type
[FaxModemBypassCo
derType]
Coder used by the device when performing fax/modem bypass. Usually,
high-bit-rate coders such as G.711 should be used.
 [0] G.711Alaw= G.711 A-law 64 (default).
 [1] G.711Mulaw = G.711 µ-law.
Fax/Modem Bypass
Packing Factor
[FaxModemBypassM]
Number of (20 msec) coder payloads that are used to generate a
fax/modem bypass packet.
The valid range is 1, 2, or 3 coder payloads. The default value is 1 coder
payload.
CNG Detector Mode
[CNGDetectorMode]
Determines whether the device detects the fax Calling tone (CNG).
 [0] Disable = The originating device doesn’t detect CNG; the CNG signal
passes transparently to the remote side (default).
 [1] Relay = CNG is detected on the originating side. CNG packets are
sent to the remote side according to T.38 (if IsFaxUsed = 1) and the fax
session is started. A Re-INVITE message isn’t sent and the fax session
starts by the terminating device. This option is useful, for example, when
the originating device is located behind a firewall that blocks incoming
T.38 packets on ports that have not yet received T.38 packets from the
internal network (i.e., originating device).
 [2] Events Only = CNG is detected on the originating side and a fax
session is started by the originating side using the Re-INVITE message.
Usually, T.38 fax session starts when the ‘preamble’ signal is detected
by the answering side. Some SIP devices don’t support the detection of
this fax signal on the answering side and thus, in these cases it is
possible to configure the device to start the T.38 fax session when the
CNG tone is detected by the originating side. However, this mode is not
recommended.