Each VoIP Bearer port can have up to seven individual Codecs configured under it. The Vocoder Profile object pane gives a user the ability to specify a codec or payload type such as G.711 ulaw etc. Maximum, Minimum, and Preferred payload types can also be modified through the drop down menu. Once created under the IP Profile object, the IMG 2020 IP signaling stacks will negotiate their use in the order in which they appear in the under the IP Profile object in the Web GUI. The priority with which the codecs are selected and utilized is determined by what position in the Web GUI tree the codec is positioned. If the codec is positioned at the top of the IP Profile codec list, it gets highest priority and the priority gets lower as the codec is positioned lower down the list. However, the priority of the codec can be changed by clicking on the codec icon in the configuration tree and dragging the codec up or down the IP Profile list of codecs. If a blue bar appears while moving the object, that indicates the object can be moved to that location. If a red circle with a line though it appears while moving the object, that indicates the object cannot be moved to that location. The screen capture just below displays a red circle with a line through it indicating the object could not be moved to that specific location in the Web GUI configuration tree.
Web GUI Page
Dialogic > Profiles > IP Profiles > IP Profile > New Vocoder Profile
AMR
AMR-WB
Maximum Objects
Up to seven Vocoder Profile entries per IP Profile object.
Related Topics and Dependencies
No dependencies.
Field Descriptions
Payload Type
This field has a drop down menu with a list of all the codecs supported on the IMG 2020. Below is a list of the supported codecs:
Codec | Description |
AMR | AMR is an audio data compression scheme for speech encoding. AMR is used in GSM and UMTS networks. AMR encodes narrowband signals at variable bit rates ranging from 4.75 to 12.2Kbps. (RFC 3267). |
AMR-WB | Refer to the topic for information on this codec. (RFC 3267). |
Clear Channel | Refer to the Clear Channel Codec Support topic for information on this codec. |
G711 alaw | Also known as PCM (Pulse Code Modulation). Has a 64 Kbps bitrate and is primarily utilized in most countries outside North America. |
G711 ulaw | Also known as PCM (Pulse Code Modulation). Has a 64 Kbps bitrate and is primarily utilized in North America. |
G723 5.3 Kbps | Standard speech codec which uses ADPCM. Transmits at 5.3Kbps. |
G723 6.3 Kbps | Standard speech codec which uses ADPCM. Transmits at 5.3Kbps. |
G729 | Audio data compression algorithm for voice. Used primarily in VoIP applications where bandwidth must be conserved. |
G722 | An ITU-T standard 7 kHz wideband speech codec operating at 48, 56 and 64 kbit/s. G.722 sample audio data at a rate of 16 kHz (using 14 bits), double that of traditional telephony interfaces, which results in superior audio quality and clarity. G722 64 bit is supported in BDN. |
iLBC 20ms | This is the Internet Low Bit-rate Codec which is approved as a standard codec by IETF as RFC 3951. It operates on 8 kHz speech frames of 20 ms corresponding to rates of 15.2 kbps. |
iLBC 30ms | This is the Internet Low Bit-rate Codec which is approved as a standard codec by IETF as RFC 3951. It operates on 8 kHz speech frames of 30 ms corresponding to rates of 13.3 kbps. |
GSM-FR Static Payload Type | A GSM full-rate wireless codec based on GSM 06.10 with a frame size of 20 ms and operates on 8 kHz speech. It is based on ETSI standards. The bit rate is 13.2 kbps. |
GSM-FR Dynamic Payload Type | Same as GSM-FR but supports a dynamic payload. |
G726-32/G721 Static Payload Type | G.726 is a standard voice codec which traditionally supports transmission rates of 16, 24, 32 or 40 kbit/sec. The IMG 2020 supports only the 32 kbit/sec rate which is optimal for voice transmission, and is also referred to as G.721. This codec uses a default static payload type of 2. |
G726-32/G721 Dynamic Payload Type | Same as G.726-32/G.721 but supports a dynamic payload type in the 96 - 127 range. |
GSM-EFR | GSM-EFR denotes the GSM 06.60 enhanced full-rate coding, specified in ETS 300 726. It has a frame size of 20 ms and operates on 8 kHz speech. The bit rate is 12.2 kbps. |
Refer to the SIP Codec Negotiation topic for payload size information on each of the codecs.
Preferred Payload Size (ms)
The Preferred Payload Size field specifies the desired payload size for the selected Payload Type. The preferred payload size can be changed by using the drop down menu in that field. Refer to the topics for more information on Codec/Payload Size Negotiation.
Minimum Payload Size (ms)
The Minimum Payload Size field specifies the minimum payload size for the selected Payload Type. The minimum payload size can be changed by using the drop down menu in that field. See Codec/Payload Selection and SIP Codec Negotiation Priority selection topics for more information on Codec/Payload Size Negotiation.
Maximum Payload Size (ms)
The Maximum Payload Size field specifies the maximum payload size for the selected Payload Type. The maximum payload size can be changed by using the drop down menu in that field. See Codec/Payload Selection and SIP Codec Negotiation Priority selection topics for more information on Codec/Payload Size Negotiation.
Default Payload Type
If the payload type is static then it must be used. If the payload type is dynamic then it is selectable. Below are the Codecs that currently support a dynamic payload type.
Codec | Payload Type | Default |
AMR | 97-127 | 97 |
AMR-WB | 96-127 | 110 |
AMR-NB Bandwidth-Efficient | 97-127 | 99 |
AMR-WB Bandwidth-Efficient | 96-127 | 100 |
Clear Channel | 96-127 | 125 |
iLBC (20 ms) | 96-127 | 96 |
iLBC (30 ms) | 96-127 | 97 |
G726-32 Dynamic Payload | 96-127 | 103 |
GSM-FR Dynamic Payload | 96-127 | 98 |
GSM-EFR | 96-127 | 102 |
Annex B Support (G.729A)
Annex B Support selection in this menu only applies to how the SIP SDP will use the annexb= string during codec negotiation. This is a SIP-specific parameter. By the RFC standards 3555/4856, annexb= can be used with the G.729A vocoder to negotiate silence suppression usage (Refer to the table below for all negotiation scenarios), but at the RTP media level Annex B defines the silence suppression algorithm for G.729A (hence G.729A/B).
In this drop down menu, the user can decide how the SIP/SDP annexb= string will be utilized. The selections are Annex B=No, Annex B=Yes. This option is currently supported only in G.729A, when SIP is the IP signaling protocol. When configuring the G.729A codec, the Annex B field is defaulted to Yes. See Below for more information.
If the user selects No in the drop down menu then the media attribute Annex B=no is sent by the IMG 2020 in the SDP portion of the SIP message when enforcing the use of the G.729 payload type. In this case, the silence suppression algorithm is not added to the G.729A codec.
If the user selects Yes in the drop down menu then the Annex-B message will not be displayed in the SDP portion of the SIP message. This value is implied when unspecified in the SDP. In this case, the silence suppression algorithm is added to the G.729A codec.
If G.729A Codec is not being used then the Web GUI will disable the Annex B support field and it will not be visible.
Annex B Ingress
When configuring G.729A codec the manner in which the Annex B Parameter is handled has been redesigned to allow for many different Annex B negotiation behaviors. A field labeled Annex B Ingress was added to allow for the selection of several possible behaviors. When G.729A is selected, the Annex B and Annex B Ingress field will be opened. Use the table below to select how SDP negotiation will behave.
Annex B Ingress is for incoming call with G.729A only.
Use the table below to select how SDP negotiation will behave.
Case # | IMG 2020 Configuration | Inbound Call | IMG 2020 Response | |
Annex B Support | Annex B Ingress | |||
1 | Yes | Disabled (Default) | Yes | Respond with Yes |
2 | Yes | Disabled (Default) | No | Respond with no a-line |
3 | Yes | Disabled (Default) | No a-line | Respond with no a-line |
4 | No | Disabled (Default) | Yes | Reject call with 488 |
5 | No | Disabled (Default) | No | Respond with No |
6 | No | Disabled (Default) | No a-line | Respond with No |
7 | Yes | Reject Call, if different | Yes | Respond with Yes |
8 | Yes | Reject Call, if different | No | Reject call with 488 |
9 | Yes | Reject Call, if different | No a-line | Respond with no a-line |
10 | No | Reject Call, if different | Yes | Reject call with 488 |
11 | No | Reject Call, if different | No | Respond with No |
12 | No | Reject Call, if different | No a-line | Reject call with 488 |
13 | Yes | Echo Received | Yes | Respond with Yes |
14 | Yes | Echo Received | No | Respond with No |
15 | Yes | Echo Received | No a-line | Respond with no a-line |
16 | No | Echo Received | Yes | Respond with Yes |
17 | No | Echo Received | No | Respond with No |
18 | No | Echo Received | No a-line | Respond with no a-line |
19 | Yes | Send Configured | Yes | Respond with Yes |
20 | Yes | Send Configured | No | Respond with Yes |
21 | Yes | Send Configured | No a-line | Respond with Yes |
22 | No | Send Configured | Yes | Respond with No |
23 | No | Send Configured | No | Respond with No |
24 | No | Send Configured | No a-line | Respond with No |
Payload Format
Specifies the payload format.
Octet Align
Bandwidth Efficient
mode-set
Specifies the mode-set parameter (this is a multi-choice selection).
AMR
Any
mode 0: 4.75 kbps
mode 1: 5.15 kbps
mode 2: 5.9 kbps
mode 3: 6.7 kbps
mode 4: 7.4 kbps
mode 5: 7.95 kbps
mode 6: 10.2 kbps
mode 7: 12.2 kbps
AMR-WB
Any
mode 0: 6.60 kbps
mode 1: 8.85 kbps
mode 2: 12.65 kbps
mode 3: 14.25 kbps
mode 4: 15.85 kbps
mode 5: 18.25 kbps
mode 6: 19.85 kbps
mode 7: 23.05 kbps
mode 8: 23.85 kbps
Initial Transmission Rate
Specifies the initial transmission rate at which IMG 2020 should start sending the AMR RTP.
Highest bit rate (Default)
Lowest bit rate