Configuring Cisco Nse For Fax; Configuring The Dejitter Buffer (Advanced) - Patton electronics SmartWare R.3.20 Software Configuration Manual

SmartWare Software Configuration Guide
NSEs are normally sent with RTP payload type 100. The RTP packets have the same source and destination
IP addresses and UDP ports as the other packets in the media stream, but differ in the RTP payload types so
they can be distinguished from the stream's audio packets.
Mode: Profile VoIP
Step Command
node(pf-voip)[ name ]#rtp payload-type nse
1
payload-type
Configuring Cisco NSE for Fax
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-vbd' is 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 de-jitter buffer for data reception. Afterwards it issues the NSE Event 193 to
trigger the calling peer to switch off Echo-Cancellation.
Configuring the dejitter buffer (advanced)
Packet networks always introduce a certain amount of jitter in the arrival of voice packets. To compensate for
the fluctuating network conditions, a dejitter buffer is integrated in the RTP processing engine. Typical voice
sources generate voice packets at a constant rate, the matching voice decompression algorithm also expects
incoming voice packets to arrive at a constant rate. However, the packet-by-packet delay inflicted by the net-
work may be different for each packet. As shown in
sent equally spaced from the left-hand gateway arrive irregularly spaced at the right-hand gateway.
VoIP profile configuration task list
Purpose
Specifies the RTP payload-type for Named Sig-
naling Events (NSE).
Default: 100
figure 80, the result of the delays is that packets which are
40 • VoIP profile configuration
513