Configuring Allowed Audio Coder Groups

The Allowed Audio Coders Groups table lets you configure up to 20 Allowed Audio Coders Groups. For each Allowed Audio Coders Group, you can configure up to 10 audio coders. The coders can include pre-defined coders and user-defined (string) coders for non-standard or unknown coders.

Allowed Audio Coders Groups restrict coders for SIP entities. Only coders listed in the Allowed Audio Coders Group (i.e., allowed coders) that is associated with the SIP entity can be used. If the coders in the SDP offer ('a=rtpmap' field) of the incoming SIP message are not listed in the Allowed Audio Coders Group, the device rejects the calls, unless transcoding is configured, whereby "extension" coders are added to the SDP, as described in Coder Transcoding. If the SDP offer contains some coders that are listed in the Allowed Audio Coders Group, the device manipulates the SDP offer by removing the coders that are not listed in the Allowed Audio Coders Group, before routing the SIP message to its destination. Thus, only coders that are common between the coders in the SDP offer and the coders in the Allowed Audio Coders Group are used. For more information on coder restriction, see Restricting Audio Coders.

For example, assume the following:

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The SDP offer in the incoming SIP message contains the G.729, G.711, and G.723 coders.

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The allowed coders configured for the SIP entity include G.711 and G.729.

The device removes the G.723 coder from the SDP offer, re-orders the coder list so that G.711 is listed first, and sends the SIP message containing only the G.711 and G.729 coders in the SDP.

To apply an Allowed Audio Coders Group for restricting coders to a SIP entity:

Configure an Allowed Audio Coders Group in the Allowed Audio Coders Groups table (see description below).

In the IP Profile associated with the SIP entity (see Configuring IP Profiles):

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Assign the Allowed Audio Coders Group, using the 'Allowed Audio Coders' parameter.

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Enable the use of Allowed Audio Coders Groups, by configuring the 'Allowed Coders Mode' parameter to Restriction or Restriction and Preference.

The device also re-orders (prioritizes) the coder list in the SDP according to the order of appearance of the coders listed in the Allowed Audio Coders Group. The first listed coder has the highest priority and the last coder has the lowest priority. For more information, see Prioritizing Coder List in SDP Offer.

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The Allowed Audio Coders Group for coder restriction takes precedence over the Coder Group for extension coders. In other words, if an extension coder is not listed as an allowed coder, the device doesn't add the extension coder to the SDP offer.

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To configure "extension" coders for adding to the SDP offer for audio transcoding, use the Coders Groups table (see Configuring Coder Groups

The following procedure describes how to configure Allowed Audio Coders Groups through the Web interface. You can also configure it through ini file [AllowedAudioCodersGroups] and [AllowedAudioCoders] or CLI (configure voip > coders-and-profiles allowed-audio-coders-groups; configure voip > coders-and-profiles allowed-audio-coders < group index/coder index>).

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To configure an Allowed Audio Coders Group:

Open the Allowed Audio Coders Groups table (Setup menu > Signaling & Media tab > Coders & Profiles folder > Allowed Audio Coders Groups).

Click New; the following dialog box appears:

Configure a name for the Allowed Audio Coders Group according to the parameters described in the table below.

Click Apply.

Select the new row that you configured, and then click the Allowed Audio Coders link located below the table; the Allowed Audio Coders table opens.

Click New; the following dialog box appears:

Configure coders for the Allowed Audio Coders Group according to the parameters described in the table below.

Click Apply.

Allowed Audio Coders Groups and Allowed Audio Coders Tables Parameter Descriptions

Parameter

Description

Allowed Audio Coders Groups Table

'Index'

allowed-audio-coders-groups <index>

[Index]

Defines an index number for the new table row.

Note: Each row must be configured with a unique index.

'Name'

coders-group-name

[Name]

Defines a descriptive name, which is used when associating the row in other tables.

The valid value is a string of up to 40 characters.

Note:

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Configure each row with a unique name.

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The parameter value cannot contain a forward slash (/).

Allowed Audio Coders Table

'Index'

allowed-audio-coders <group index > coder index>

[AllowedAudioCodersIndex]

Defines an index number for the new table row.

For a list of supported coders, see

Note: Each row must be configured with a unique index.

'Coder'

coder

[CoderID]

Defines a coder from the list of coders.

Note: Each coder can be configured only once per Allowed Audio Coders Group.

'User-defined Coder'

user-define-coder

[UserDefineCoder]

Defines a user-defined coder.

The valid value is a string of up to 24 characters (case-insensitive). For example, "HD.123" (without quotation marks).

Note: Each coder can be configured only once per Allowed Audio Coders Group.