Packet Service Profile - Packet To Packet Control

This control specifies the transcoding method used for the associated packet flow.

The SBC performs transcoding for media streams carried between two IP devices by translating the streams from the ingress audio encoding format to the egress audio encoding format when the devices do not share a common codec. In some environments, transcoding may be preferred over negotiating the attributes of a common codec.

• Conditional—The SBC performs transcoding when any of the conditions specified in the Conditions In Addition To "No Common Codec" section are met.
• Determined By PSP For Other Leg—The SBC performs transcoding based on the transcoding options specified in the packet service profile assigned to the other leg of the call. When selected, PSX Manager disables the check boxes in the Codecs Allowed for Transcoding section.
• Only—The SBC performs transcoding for the codecs selected in the Codec Allowed For Transcoding section (see definition below). None of the conditions specified in the Conditions In Addition To "No Common Codec" section are used in determining when to perform transcoding.
• Transcoder Free Transparency—When selected, the SBC transparently passes the PSP from the ingress call-leg to the egress call-leg, bypassing transcoding.

NOTE: The SBC, when configured with the appropriate codecs, transcodes for differences in the codecs. Use ‘transcode conditional’ option to allow the SBC to transcode for certain conditions in addition to differences in codecs. For example, if the codecs are the same on both legs and this option is selected, by applying additional settings for the particular call scenarios, the SBC will trigger transcoding for those scenarios, such as:

1. Transcode for DTMF differences. For example, when both legs have same codec, but one uses inband for DTMF and the other RFC 2833.
2. Transcode for Silence Suppression differences.
3. Transcode for Packet Size differences.
4. Transcode for RFC2833/4733 Payload differences. For example, when codecs are the same on both legs, but one side uses 101 as the Payload Type for DTMF and the other uses 102.
5. Transcode always.

Note:

• If Packet To Packet Control is configured for “Transcode Free Transparency”, ensure that Late Media Support is set to ‘passthru’.
• Transcoder Free Transparency takes precedence over PSP flags when enabled on either the ingress trunk group or egress trunk group PSP leg, thus allowing the SBC to bypass transcoding and codec policies that result in removing/deleting codecs.