AudioCodes Mediant 4000 SBC - Fax; Modem NSE Mode; Fax; Modem Transparent with Events Mode

CHAPTER15 Media
Mediant 4000 SBC | User's Manual
Fax / Modem NSE Mode
In this mode, fax and modem signals are transferred using Cisco-compatible Pass-through bypass
mode. Upon detection of fax or modem answering tone signal, the terminating device sends three
to six special NSE RTP packets (configured by the NSEpayloadType parameter; usually to 100).
These packets signal the remote device to switch to G.711 coder, according to the 'Fax/Modem
Bypass Packing Factor' parameter. After a few NSE packets are exchanged between the devices,
both devices start using G.711 packets with standard payload type (8 for G.711 A-Law and 0 for
G.711 Mu-Law). In this mode, no Re-INVITE messages are sent. The voice channel is optimized
for fax/modem transmission (same as for usual bypass mode).
The following parameters that configure the payload type for the AudioCodes proprietary Bypass
mode are not used with NSE Bypass: 'Fax Bypass Payload Type' and
[ModemBypassPayloadType].
When configured for NSE mode, the device includes the following line in the SDP, where 100 is the
NSE payload type:
a=rtpmap:100 X-NSE/8000
The Cisco gateway must include the following definition:
modem passthrough nse payload-type 100 codec g711alaw
➢ To configure NSE mode:
1. On the Fax/Modem/CID Settings page, do the following:
● Set the 'Fax Transport Mode' parameter to Bypass (FaxTransportMode = 2).
● Set the 'V.21 Modem Transport Type' parameter to Enable Bypass
(V21ModemTransportType = 2).
● Set the 'V.22 Modem Transport Type' parameter to Enable Bypass
(V22ModemTransportType = 2).
● Set the 'V.23 Modem Transport Type' parameter to Enable Bypass
(V23ModemTransportType = 2).
● Set the 'V.32 Modem Transport Type' parameter to Enable Bypass
(V32ModemTransportType = 2).
● Set the 'V.34 Modem Transport Type' parameter to Enable Bypass
(V34ModemTransportType = 2).
2. Set the ini file parameter [BellModemTransportType] to [2] (Bypass).
3. Set the ini file parameter [NSEMode] parameter to [1] (enables NSE).
4. Set the ini file parameter [NSEPayloadType] parameter to [100].
Fax / Modem Transparent with Events Mode
In this mode, fax and modem signals are transferred using the current voice coder with the following
automatic adaptations:
■ Echo Canceller = on (or off for modems)
■ Echo Canceller Non-Linear Processor Mode = off
■ Jitter buffering optimizations
➢ To configure fax / modem transparent with events mode:
1. On the Fax/Modem/CID Settings page, do the following:
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