The SBC Core supports playing announcements that are stored in G.711ULaw format. The SBC Core is enhanced to support playing compressed tones directly without allocating DSP resources by playing the tones from the pre-encoded files with various combinations of tones and codec types. The tone files are created for the required tone types with different codec combinations and stored as
.wav files in the SBC. For the compressed tones, the ptime is fixed to 20 milliseconds for EVRC/EVRCB and AMR-WB codecs.
The SBC Core is enhanced in this release with a new media profile,
tonesAsAnnouncement, which includes the following parameters to configure the announcement file to play Local Ringback Tone (LRBT) for each codec entry:
The existing Tone Profile references the
toneType in the
tonesAsAnnouncement profile, whereas the new object
toneCodecEntry references the
codecType. With this enhancement, the user can associate default Tone Profile or can create a customized Tone Profile and assign it to the
toneType of the
toneAsAnnouncementProfile. The flag
announcementBasedTones is included in
toneAndAnnouncementProfile configuration to play ringback tones without using DSP resources.
The SBC supports playing tones for three groups of codecs. If the required tone playback falls under one of the following codecs and the flag
announcementBasedTones is enabled, the SBC must avoid allocating DSP resources and play a tone as an announcement. If the required tone playback does not fall under one of the following codecs and the flag
announcementBasedTones is enabled, the SBC does not fall back to the DSP mode and continues the call without playing the tones.
The SBC supports playing default ringtones with 15 different types of codec variants.
The compressed tone files are stored in the standard
.wav file format. The SBC uses the same naming convention for the compressed tone files as the announcement files. For example, in a
sDDDDD.wav file, where DDDDD is a decimal number from 1 to 65,535, the decimal number represents the segment ID of the file.
The announcement and the tone files share the 5-bit segment ID space, and thus, every file name must have a unique segment ID. The compressed tone files are stored in the same directory path as the announcement files
/var/log/sonus/sbx/announcements). The tone file is played continuously until the tone is stopped due to a trigger.
The following table provides the
.wav file mapping information for the application announcements:
The SBC supports playing tones when an Alert-Info header is received in the Legacy Mobile Station Domain (LMSD) format (Alert-Info: <http:/LMSD/tone?sig-id=rt>). The SBC is enhanced to play the ringback tone without using DSP resources whenever it receives 180 with Session Description Protocol (SDP) answer with Alert-Info header (Alert-Info: <http:/LMSD/tone?sig-id=rt>). The Alert-Info header, present in the 180 ringing with SDP, carries the tone package information required by the SBC to play ringback tone. To support this feature, the existing LRBT framework is enhanced.
The SBC supports generating LRBT when:
acceptAlertInfois enabled on the egress TG.
toneAndAnnouncementProfileassociated with the ingress TG is enabled.
The SBC supports fallback to LMSD interworking state, if the flag
The SBC plays tones using the “lock down" preferred codec when the following flags are enabled:
The codec, which is used for playing tone towards the ingress leg, is based on whether the session is established as pass-through or transcoded. If the SBC receives SDP answer from the egress peer, the selected codec is the egress peer's preferred codec. However, the ingress peer's preferred codec is used to play the tone, if the session outcome is transcoding.
The SBC plays tones when it receives 180 responses with SDP for the egress peer preferred codec. When the 180 response is received without SDP from the egress peer, the SBC plays ringback tones based on the existing LRBT implementation using the ingress peer preferred codec. For more information on LRBT, refer to Tone and Announcement Profile - CLI.
The SBC is enhanced to stop playing ringback tones upon receipt of any of the following messages: