AudioCodes MSBG Series User Manual

Version 7.2 425 Mediant 1000B Gateway & E-SBC
User's Manual 19. Coders and Profiles
Parameter Description
fax-sig-method
[IpProfile_IsFaxUsed]
fax session when the device detects a fax.
 [0] No Fax = (Default) No fax negotiation using SIP signaling. The
fax transport method is according to the FaxTransportMode
parameter.
 [1] T.38 Relay = Initiates T.38 fax relay.
 [2] G.711 Transport = Initiates fax/modem using the coder G.711
A-law/Mu-law with adaptations (see Note below).
 [3] Fax Fallback = Initiates T.38 fax relay. If the T.38 negotiation
fails, the device re-initiates a fax session using the coder G.711
A-law/Mu-law with adaptations (see the Note below).
Note:
 Fax adaptations (for options 2 and 3):

Echo Canceller = On

Silence Compression = Off

Echo Canceller Non-Linear Processor Mode = Off

Dynamic Jitter Buffer Minimum Delay = 40

Dynamic Jitter Buffer Optimization Factor = 13
 If the device initiates a fax session using G.711 (option 2 or 3), a
'gpmd' attribute is added to the SDP in the following format:

For A-law: 'a=gpmd:8 vbd=yes;ecan=on'

For Mu-law: 'a=gpmd:0 vbd=yes;ecan=on'
 When the parameter is set to 1, 2, or 3, the parameter
FaxTransportMode is ignored.
 When the parameter is set to 0, T.38 might still be used without
the control protocol's involvement. To completely disable T.38,
set FaxTransportMode to a value other than 1.
 For more information on fax transport methods, see Fax/Modem
Transport Modes on page 179.
 The corresponding global parameter is IsFaxUsed.
CNG Detector Mode
cng-mode
[IpProfile_CNGmode]
Enables the detection of the fax calling tone (CNG) and defines the
detection method.
 [0] Disable = (Default) The originating fax does not detect CNG;
the device passes the CNG signal transparently to the remote
side.
 [1] Relay = The originating fax detects CNG. The device sends
CNG packets to the remote side according to T.38 (if IsFaxUsed
is set to 1) and the fax session is started. A SIP Re-INVITE
message is not sent and the fax session starts by the terminating
fax. This option is useful, for example, when the originating fax 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 fax). To also send a Re-INVITE message
upon detection of a fax CNG tone in this mode, set the parameter
FaxCNGMode to 1.
 [2] Event Only = The originating fax detects CNG and a fax
session is started by the originating fax, using the Re-INVITE
message. Typically, T.38 fax session starts when the preamble
signal is detected by the answering fax. Some SIP devices do not
support the detection of this fax signal on the answering fax 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

AudioCodes MSBG Series Specifications

General

Brand	AudioCodes
Model	MSBG Series
Category	Gateway
Language	English