User`s manual

SIP User's Manual 402 Document #: LTRT-83303
Mediant 1000 & Mediant 600
When configured for NSE mode, the device includes in its SDP the following line:
a=rtpmap:100 X-NSE/8000
(where 100 is the NSE payload type)
The Cisco gateway must include the following definition: "modem passthrough nse
payload-type 100 codec g711alaw".
To configure NSE mode, perform the following configurations:
 IsFaxUsed = 0
 FaxTransportMode = 2
 NSEMode = 1
 NSEPayloadType = 100
 V21ModemTransportType = 2
 V22ModemTransportType = 2
 V23ModemTransportType = 2
 V32ModemTransportType = 2
 V34ModemTransportType = 2
 BellModemTransportType = 2
7.2.2.4 G.711 Fax / Modem Transport Mode
In this mode, when the terminating device detects fax or modem signals (CED or AnsAM),
it sends a Re-INVITE message to the originating device requesting it to re-open the
channel in G.711 VBD with the following adaptations:
 Echo Canceller = off
 Silence Compression = off
 Echo Canceller Non-Linear Processor Mode = off
 Dynamic Jitter Buffer Minimum Delay = 40
 Dynamic Jitter Buffer Optimization Factor = 13
After a few seconds upon detection of fax V.21 preamble or super G3 fax signals, the
device sends a second Re-INVITE enabling the echo canceller (the echo canceller is
disabled only on modem transmission).
A ‘gpmd’ attribute is added to the SDP according to the following format:
 For G.711A-law: a=gpmd:0 vbd=yes;ecan=on (or off, for modems)
 For G.711 µ-law: a=gpmd:8 vbd=yes;ecan=on (or off for modems)
The parameters FaxTransportMode and VxxModemTransportType are ignored and
automatically set to the mode called ‘transparent with events’.
To configure fax / modem transparent mode, set IsFaxUsed to 2.
7.2.2.5 Fax Fallback
In this mode, when the terminating device detects a fax signal, it sends a Re-INVITE
message to the originating device with T.38. If the remote device doesn’t support T.38
(replies with 415 Media Not Supported), the device sends a new Re-INVITE with G.711
VBD with the following adaptations: