Tones and Announcements

 

The

supports playing announcements, tones, and collecting digits.

Tone and Announcement Profile

Tones and announcements are configured by allocating a percentage of DSP cores to tones/announcements. If no transcoding is used, you may allocate up to 100% toward tones/announcements.

Announcements are customized by provisioning announcement packages using Media Profile on the

. An announcement package supports provisioning of up to 16 announcement names to segment ID mapping. For more information on configuring Media Profiles, see Media Profile - CLI or Profile Management - Media Profiles.

When using an external PSX, the PSX returns the tones/announcement profile and announcement or tone to be played in policy/trigger response. The

plays out the specified announcement/tone using the specified profile.

Announcement files are stored in the directory:  /var/log/sonus/evlog/announcements

For more information on configuring tones and announcements, see following:

• CLI: Tone and Announcement Profile - CLI
• EMA: Tone And Announcement Profile - Tone And Announcement

Tone Profile

The

supports a default tone package with a package ID of “1”. The default package contains the following default tone profile definitions.

• defBusy
• defCallWaiting1
• defCallWaiting2
• defCallWaiting3
• defCallWaiting4
• defCpeAlerting
• defDial
• defReorder
• defRing
• defSit1
• defSit2
• defSit3
• fccBusy
• fccDial
• fccRingback

Tones are customized by provisioning tone packages and tone profiles. The tone profile feature supports tone generation methods as described in Table 1.

For details to configure tone profiles, see below:

• CLI: Tone Profile - CLI
• EMA: Media Profiles - Tone Profile, Media - Tone Profile

Local Ring Back Tones (LRBT)

The 

is configurable to support LRBT as described below:

The

generates LRBT in the following conditions:

• Start LRBT upon receipt of 180 without SDP, the
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  .
• Halt LRBT upon receipt of any18x with SDP or any final response.
• Stop LRBT without waiting for media packet arrival.

The

supports the following dynamic LRBT functionality related to RFC 3960:

• Do not generate local ringing unless a 180 ringing response with SDP is received.
• Generate local ringing if a 180 ringing is received but no incoming media packets are present from the UAS.
• If incoming media packets are received from the UAS, play incoming packets and stop playing the tone.

When configured to operate with an external PSX, local ring back tones are provisioned on the PSX on a per-trunk group basis. The PSX returns this information in a policy response.

In a pass-through call scenario, the 

is prevented from selecting the preferred codec of the ingress offer to play the LRBT. The ingress offer codec may differ from the early answer codec that is used for the end to end cut-thru, and this change in codec can cause a media glitch to the ingress user. The  instead plays the LRBT with the same codec as the early answer codec that was received from egress (see the following call flow). The end to end cut-thru also uses the codec that plays the LRBT. The codec used between early media and to play tones therefore remains consistent. 

Playing Tones as Announcements

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. All these tones are stored with a ptime of 20 milliseconds.

The SBC Core includes the media profile tonesAsAnnouncement which uses the following parameters to configure the announcement file to play LRBT for each codec entry:

• toneType
• codecType
• segmentId

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 LRBT without using DSP resources.

The SBC supports playing tones for seven groups of codecs. If the required tone playback falls under one of the following codecs and the flag annoucementBasedTones 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 annoucementBasedTones is enabled, the SBC does not fall back to the DSP mode and continues the call without playing the tones.

• G.711 (G.711ALaw and G.711ULaw)
• G.722
• EVRC (EVRC, EVRC0, EVRCB, and EVRCB0)
  
• amrwbBandwidthEfficient (AMR-WB-BWE, 9 variants)

• amrwbOctetAligned (AMR-WB-OA, 9 variants)

• amrBandwidthEfficient (AMR-NB-BWE, 8 variants)

• amrOctetAligned (AMR-NB-OA, 8 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:

LMSD - Tone Play Support

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 LRBT 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 LRBT. To support this feature, the existing LRBT framework is enhanced.  

The SBC supports generating LRBT when:

• The flag acceptAlertInfo is enabled on the egress TG.
• The provisional response is 180 ringing with SDP and the tone flavor is normal.
• The P-Com.DropEarlyMedia header is not present in the original INVITE.
• The SDP answer is received in 180 or in a previous provisional response (183).
• The 180 contains an Alert-Info header having sig-id = “rt” only (bt/ct does not play tone).
• The flag announcementBasedTone in the toneAndAnnouncementProfile associated with the ingress TG is enabled.

LMSD - Playing Tones Using Lock Down Preferred Codec

The SBC plays tones using the “lock down" preferred codec when the following flags are enabled:

• sendOnlyPreferredCodec (IPSP)

• honorRemotePrecedence (PSP)
• announcementBasedTones

The codec that 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.

LMSD - Handling UPDATEs for the Tones

 The SBC is enhanced to stop playing LRBT upon receipt of any of the following messages:

• UPDATE message with different SDP
• subsequent 183 with SDP
• 200 OK with or without SDP

For more information on Tone and Announcement feature, refer to:

• Tone and Announcement Alarm for SBC SWe Cloud.
• Tone and Announcement Profile - CLI

 Alert-Info and P-Early Media Headers Interworking

The SBC supports the following Alert-Info to P-Early Media interworking functionality using the SIP trunk group flag aiToPemInterworking:

• Interworking between a network supporting Alert-Info header (based on the Legacy Mobile Station Domain (LMSD) format) to a network supporting P-Early Media header. The SBC supports interworking irrespective of the existence of a provisioned tone on the SBC.
• Interworking between a network that does not support P-Early Media header to a network that supports P-Early Media header. For example, the ingress network supports P-Early Media header; however, the egress network does not.
• Interworking between networks that support P-Early Media headers.

These functionalities interact with each other based on the Trunk Group and Signaling profile configuration on the SBC, to which tone profile is configured and attached:

When a tone is configured on the SBC,

• If the flag aiToPemInterworking is disabled on the egress TG, the SBC plays tone based on the LMSD format. For more information, refer to Tones and Announcements. 

• If the flag aiToPemInterworking is enabled on the egress TG, the SBC supports interworking between Alert-Info and P-Early Media headers. The SBC plays tone when it receives Alert-Info header with sig-id=rt in the 180 provisioning response (either first 180 response or subsequent 180 response) from the Mobile Switching Center (MSC) (CDMA network). 
  

  Note

  • When all the tone playing criteria are fulfilled, the SBC inserts P-Early Media header as SENDRECV (P-Early Media: SENDRECV) and sends it towards the ingress network.

  • When the SBC fails to play tone, the SBC inserts P-Early Media header as INACTIVE (P-Early Media: INACTIVE) and sends it towards the ingress network.

When tone is not configured on the SBC; and the IPSP flag acceptAlertInfo is enabled on the egress TG, and the INVITE message is received with P-Early Media: SUPPORTED,

• If the flag aiToPemInterworking is disabled on the egress TG, the SBC falls back to the existing LMSD interwoking functionality. For more information, refer to LMSD Interworking without Tones.
  

• If the flag aiToPemInterworking is enabled on the egress TG, the SBC supports interworking between Alert-Info header (received in the LMSD format) and P-Early Media header.
   

  Note

  • When the User-Agent Server (UAS) plays tone, the SBC inserts P-Early Media header as SENDRECV (P-Early Media: SENDRECV) and sends it towards the ingress network.
  • When the User-Agent Client (UAC) plays tone, the SBC inserts P-Early Media header as INACTIVE (P-Early Media: INACTIVE) and sends it towards the ingress network.