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In this section:

Overview

The Ribbon D-SBC supports the following tones/announcement functionality:

  • Generating early-media/tones/announcements with pre-recorded tone files for a specific set of codecs with a ptime of 20ms without using DSP resources.
  • Playing announcements based on a script provided by the PSX. 
  • Playing tones and announcements using tone DSPs from the T-SBC based on existing Local Ringback Tone (LRBT) configuration controls (see Local Ringback Tone Configuration Controls for details).

While playing announcements, the D-SBC also supports:

  • Two-stage calls

  • Error-Info based and Disconnect Treatment announcements

  • Provisioning a custom profile to specify the percentage of tone DSP resources (TPADs).

Local Ringback Tone Configuration Controls

If tones/announcements are played using the DSP, the announcement resource (ARES) is also allocated on the T-SBC so that both the TPAD and the announcement resources reside on the same node.

When playing a ringback tone using a compression codec, the PXPAD (for tone context) and TPAD are allocated on the same T-SBC instance, which can differ from a T-SBC hosting the DSPs used for cut-through. Hence, while allocating PXPAD for tone context, the S-SBC selects a T-SBC containing TPADs.

Table 1: D-SBC/I-SBC behavior with LRBT

LRBT Configuration Controls

D-SBC/I-SBC Behavior

Normal LRBT

  • The SBC immediately feeds the tone when it receives a first 180 without SDP.
  • After receiving the answer SDP in a 18x/2xx message, the SBC stops the tone and performs a cut-through.

Forced LRBT

  • The SBC immediately feeds the tone when it receives a provisional response (180 or 183 only), with or without an SDP answer.
  • TheSBC continues to feed the tone until it receives a final answer.
  • Subsequent SDP updates are queued until a final answer is received.

Dynamic LRBT

  • The SBC immediately feeds the tone when it receives a 180 (with or without SDP) on an answered or unanswered dialog, and starts monitoring for RTP packets if the SDP answer is already received.
  • If the first RTP packet is received, the SBC stops the tone, performs a cut-through, and discontinues monitoring.


Configuring Announcment-Based Tones

Disable the announcementBasedTones flag under the Tone And Announcement profile to use Tones and Announcements using DSP resources.

Enable the announcementBasedTones flag to use announcement-based ringback tones without using DSP resources.

  • The D-SBC continues to play tones using pre-recorded tone files.
  • If desired, use either the T-SBC cluster or the Media Resource Function (MRF) to provide transcoding.


Note

If the policy flag, announcementBasedTones, is enabled, it takes precedence over DSP-based tones using the T-SBC.

During Announcement play using DSP, for the G711 codec (without 2833), the M-SBC is used to play the announcement instead of the T-SBC. In other scenarios, the T-SBC is used to play the announcement.

Make sure the announcement .wav files are available on both  M-SBC and T-SBC for DSP based tones.