AudioCodes Mediant 500L MSBR

User's Manual 17. Media
Version 6.8 193 Mediant 500L MSBR
Notes:
• The V.150.1 Modem Relay feature is available only if the device is installed with a
Software License Key that includes this feature. For installing a Software License
Key, see ''Software License Key'' on page 638.
• The V.150.1 Modem Relay feature support is a subset of the full V.150.1 protocol
and is designed according to the US DoD requirement document. It therefore,
cannot be used for general purposes.
• The V.150.1 feature has been tested with certain IP phones. For more details,
please contact your AudioCodes sales representative.
• The V.150.1 SSE Tx payload type is according to the offered SDP of the remote
side.
• The V.150.1 SPRT Rx payload type is according to the 'Payload Type' field in the
Coders table.
• The V.150.1 SPRT Tx payload type is according to the remote side offered SDP.
 To configure V.150.1 Modem relay:
1. In the Coders Table (Configuration tab > VoIP menu > Coders and Profiles >
Coders), set the coder to V.150.
2. On the Fax/Modem/CID Settings page, configure the V.150.1 parameters appearing
under the 'V.150.1 Modem Relay Settings' group:
a. Set the 'SSE Payload Type Rx' parameter to the V.150.1 SSE payload type that
the device uses when it offers the SDP.
b. Set the 'SSE Redundancy Depth' parameter to the number of sent SSE
redundant packets. This parameter is important in case of network impairments.
c. For additional V.150.1 related parameters, see ''Fax and Modem Parameters'' on
page 886.
17.2.5 Simultaneous Negotiation of Fax (T.38) and Modem (V.150.1)
Relay
The device can negotiate fax relay (T.38) and modem relay (V.150.1) sessions in the
same, already established call channel. Fax relay sessions require bypass answering tone
(CED) while modem relay requires RFC 2833 answering tone. As the device is not always
aware at the start of the session whether the answering tone is fax or modem, it uses both
methods for CED tone transfer and sends both answering tone types. Only when the
answering tone is detected, does the device send the fax or modem.
To support this functionality, you need to configure a Coders Group (in the Coders Group
table - see ''Configuring Coder Groups'' on page 326) that includes the T.38, V.150, and
G.711/VBD coders.
17.2.6 V.152 Support
The device supports the ITU-T recommendation V.152 (Procedures for Supporting Voice-
Band Data over IP Networks). Voice-band data (VBD) is the transport of modem, facsimile,
and text telephony signals over a voice channel of a packet network with a codec
appropriate for such signals.
For V.152 capability, the device supports T.38 as well as VBD codecs (i.e., G.711 A-law
and G.711 μ-law). The selection of capabilities is performed using the coders table (see
''Configuring Default Coders'' on page 323).
When in VBD mode for V.152 implementation, support is negotiated between the device
and the remote endpoint at the establishment of the call. During this time, initial exchange