Patton electronic SmartNode 4110 Series ユーザーズマニュアル

VoIP profile configuration task list

SmartWare Software Configuration Guide 

Some SIP gateways change their port number when switching from audio to T.38. This behavior causes prob-
lems if the SmartNode is located on the A-Side behind a NAT. Due to T.30 is a unidirectional. protocol and 
the B-Side is normally the initiator of the T.30 handshaking, the SmartNode never receives the initial packets 
of the B-Side because the NAT ports are not yet opened.  

To open the NAT ports SmartWare no sends T.38 ‘no-signal’ packets when a codec change is detected. By 
default SmartNode sends 3 such packets. To adjust the number of ‘no-signal’ packets, use the following config-
uration command.

Mode: Configure/profile voip

This command specifies the method for notifying the remote device that the RTP Stream has switched to a 
voice-band FAX transmission. This feature is only available on the SIP protocol. If the command option ‘v150-
vbd’ is selected, a re-invite is sent even if the current voice coder is configured the same as the fax bypass coder. 
Furthermore the re-invite contains a gpmd-attribute line with the value ‘vbd=yes’ in the media description 
part. It signals the remote device of the new media transmission. If the command option ‘default’ is selected, 
the system behavior is the same as before.

For a fax transmission over a VoIP (SIP or H.323) network, the Cisco NSE standard uses events defined by 
RFC2833.  These events are used for the setup of the fax transmission starting between the calling- and called-
peer.    Upon detecting a fax transmission, the called-peer issues NSE Event 192.  NSE Event 192 indicates the 
data stream is via a voice band, and it forces the calling-peer to do two things—deactivate voice activity detec-
tion and reconfigure the de-jitter buffer for data reception.  The option ‘nse’ enables this fax transmission stan-
dard.

Mode: profile voip 

When using fax transmission in SIP, it is possible configure the SIP gateway to first try to use T.38 and to fall 
back to a high-rate codec, if the remote gateway does not support T.38. This can be configured as follows:

Mode: profile voip <pf-name>

[name] (pf-voip)[name]#fax nosig-
nal-retransmission [1...5]

Sets how many times a T.38 ‘nosignal’ is retrans-
mitted. Default: 3 

[name] (pf-voip)[name]#fax bypass-
method {default | v150-vbd|nse}

Specifies the fax bypass signaling method.
Default: default

[name] (pf-voip)[pf-name]# fax 
transmission 1 relay t38-udp

Define T.38 UDP as the first fax transmission 
method to try