Patton electronic SmartNode 4110 Series manual Modem bypass method, Configuring modem transmission

SmartWare Software Configuration Guide47 • VoIP profile configuration

Step	Command	Purpose
2	[name] (pf-voip)[pf-name]# fax	Define G.711 A-Law as the second fax transmis-
	transmission 2 bypass	sion method to try, if T.38 is not supported by the
	g711alaw64k	remote gateway.

Note The first codec must always be T.38, while the second one must be a high- rate codec such as G.711, which supports fax transmission.

Configuring modem transmission

Modem transmission is similar to fax transmission, except that modem data is always transported in bypass mode. This means that an ordered list of bypass codecs can be defined for modem transmission. If no modem transmission codec is configured, no action is taken to change the codec when modem is detected.

Procedure: Configure modem bypass

Mode: Profile VoIP

Step	Command			Purpose
1	node(pf-voip)[name]#modem trans-	Adds modem transmission with codec G.711 to
	mission bypass g711alaw64k	the list of fax transmission modes.Alternative
		codecs available are:
		•	G.711uLaw
		•	G.726	32kbps
		•	G.726	24kbps.

Modem bypass method

This command specifies the method to be used for signaling the remote device the RTP Stream has switched to a voice-band Modem transmission. This feature is only available on the SIP protocol. If the command option v150-vbdis selected, a re-invite will be sent even if the current voice coder is configured the same as the modem bypass coder. Furthermore the re-invite contains a gpmd-attribute line with the value vbd=yes;ecan=off in the media description part. This attribute signals the remote device of the new media transmission. If the command option default is selected, the system behavior is the same as before.

SmartWare also supports the Cisco NSE standard which uses RFC2833 events for modem transmission over a VoIP (SIP or H.323) network. Upon detecting a modem transmission, the called peer issues NSE Event 192. NSE Event 192 indicates a Voice Band Data stream that forces the calling peer to deactivate Voice Activity Detection and to reconfigure the Dejitter Buffer for data reception. Afterwards it issues the NSE Event 193 to trigger the calling peer to switch off Echo-Cancellation.

Mode: profile voip

Step	Command	Purpose
1	[ name] (pf-voip)[name]#modem	Specifies the modem bypass signaling method.
	bypass- method {default v150-	Default: default
	vbd nse}

VoIP profile configuration task list 589