AudioCodes Media Pack MP-124 - Fax and Modem Capabilities; Fax;Modem Operating Modes; Fax;Modem Transport Modes

SIP User's Manual 396 Document #: LTRT-65412
MP-11x & MP-124
9.5 Fax and Modem Capabilities
This section describes the device's fax and modem capabilities, and includes the following
main subsections:
 Fax and modem operating modes (refer to ''Fax/Modem Operating Modes''
396
on page
)
 Fax and modem transport modes (refer to ''Fax/Modem Transport Modes''
396
on page
)
 V.34 fax support (refer to ''V.34 Fax Support'' 402 on page )
 V.152 support (refer to ''V.152 Support'' 403 on page )
9.5.1 Fax/Modem Operating Modes
The device supports two modes of operations:
 Fax/modem negotiation that is not performed during the establishment of the call.
 Voice-band data (VBD) mode for V.152 implementation (refer to ''V.152 Support''
403
on
page ): fax/modem capabilities are negotiated between the device and the remote
endpoint at the establishment of the call. During a call, when a fax/modem signal is
detected, transition from voice to VBD (or T.38) is automatically performed and no
additional SIP signaling is required. If negotiation fails (i.e., no match is achieved for
any of the transport capabilities), fallback to existing logic occurs (according to the
parameter IsFaxUsed).
9.5.2 Fax/Modem Transport Modes
The device supports the following transport modes for fax per modem type
(V.22/V.23/Bell/V.32/V.34):
 T.38 fax relay (refer to ''Fax Relay Mode'' 397 on page )
 Fax and modem bypass: a proprietary method that uses a high bit rate coder (refer to
''
Fax/Modem Bypass Mode'' 398 on page )
 NSE Cisco’s Pass-through bypass mode for fax and modem (refer to ''Fax / Modem
NSE Mode'' 399 on page )
 Transparent: passing the fax / modem signal in the current voice coder (refer to ''Fax /
Modem Transparent Mode'' 400 on page )
 Transparent with events: passing the fax / modem signal in the current voice coder
with adaptations (refer to ''
Fax / Modem Transparent with Events Mode'' 400 on page )
 G.711 Transport: switching to G.711 when fax/modem is detected (refer to ''G.711 Fax
/ Modem Transport Mode'' 401 on page )
 Fax fallback to G.711 if T.38 is not supported (refer to ''Fax Fallback'' 402 on page )
‘Adaptations’ refer to automatic reconfiguration of certain DSP features for handling
fax/modem streams differently than voice.