Version 7.2 429 Mediant 500L Gateway & E-SBC
User's Manual 20. Coders and Profiles
20 Coders and Profiles
This section describes configuration of the coders and SIP profiles parameters.
20.1 Configuring Coder Groups
The Coder Groups table lets you configure up to 11 Coder Groups. The Coder Group
determines the audio (voice) coders used for calls. Each Coder Group can include up to 10
coders, where the packetization time (ptime), bit rate, payload type, and silence
suppression can be configured per coder. The first coder in the Coder Group has the
highest priority and is used by the device whenever possible. If the remote side cannot use
the first coder, the device attempts to use the next coder in the Coder Group, and so on.
The Coder Groups table provides a pre-defined Coder Group (index 0) that is configured
with the G.711 A-law coder. If no other Coder Groups are configured, the default Coder
Group (which you can modify) is used for all calls. Alternatively, if you want to use specific
coders or coder settings (e.g., packetization time) for different calls (entities), you need to
configure a Coder Group for each entity and then assign each Coder Group to the Tel
Profile (see Configuring Tel Profiles on page 471) or IP Profile (see ''Configuring IP
Profiles'' on page 438) associated with the entity (IP Group). If an IP Group is not
associated with a Coder Group, the default Coder Group is used.
Note:
• For supported audio coders, see ''Supported Audio Coders'' on page 431.
• Some coders are license-dependent and are available only if purchased from
AudioCodes and included in the License Key installed on your device. For more
information, contact your AudioCodes sales representative.
• Only the packetization time of the first coder listed in the Coder Group is declared
in INVITE/200 OK SDP even if multiple coders are configured. The device always
uses the packetization time requested by the remote side for sending RTP
packets. If not specified, the packetization time is assigned the default value.
• The value of some fields is hard-coded according to common standards (e.g.,
payload type of G.711 U-law is always 0).
• The G.722 coder provides Packet Loss Concealment (PLC) capabilities, ensuring
higher voice quality.
• Opus coder:
√ For SBC calls: If one leg uses a narrowband coder (e.g., G.711) and the other
leg uses the Opus coder, the device maintains the narrowband coder flavor by
using the narrowband Opus coder. Alternatively, if one leg uses a wideband
coder (e.g., G.722) and the other leg uses the Opus coder, the device
maintains the wideband coder flavor by using the wideband Opus coder.
√ Gateway calls always use the narrowband Opus coder.
• For more information on V.152 and implementation of T.38 and VBD coders, see
''Supporting V.152 Implementation'' on page 199.
The following procedure describes how to configure the Coder Groups table through the
Web interface. You can also configure it through ini file (AudioCodersGroups and
AudioCoders) or CLI (configure voip > coders-and-profiles audio-coders-groups).
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