The internet Low Bitrate Codec (iLBC) is a standard, high-complexity speech codec suitable for robust voice communication over IP. The iLBC has built-in error correction functionality that helps the codec perform in networks with high-packet loss. This codec is supported on both Session Initiation Protocol (SIP) and H.323.
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for iLBC Support for SIP and H.323
Cisco Unified Border Element
Cisco IOS Release 12.2(11)T or a later release must be installed and running on your Cisco Unified Border Element.
Cisco Unified Border Element (Enterprise)
Cisco IOS XE Release 2.5 or a later release must be installed and running on your Cisco ASR 1000 Series Router.
Restrictions for iLBC Support for SIP and H.323
The iLBC Support for SIP and H.323 feature is supported on the following:
IP-to-IP gateways with no transcoding and conferencing
All c5510 DSP-based platforms
Information About iLBC Support for SIP and H.323
The internet Low Bit Rate Codec (iLBC) is designed for narrow band speech and results in a payload bit rate of 13.33 kbits per second for 30-millisecond (ms) frames and 15.20 kbits per second for 20 ms frames.
When the codec operates at block lengths of 20 ms, it produces 304 bits per block, which is packetized as defined in RFC 3952. Similarly, for block lengths of 30 ms it produces 400 bits per block, which is packetized as defined in RFC 3952.
The iLBC has built-in error correction functionality to provide better performance in networks with higher packet loss.
Identifies the payload type of a Real-Time Transport Protocol (RTP) packet. Keyword and argument are as follows:
cisco-codec-ilbc [number]--Payload type is for internet Low Bit Rate Codec (iLBC). Range: 96 to 127. Default: 116.
Note
Do not use the following numbers because they have preassigned values: 96, 97, 100, 117, 121 to 123, and 125 to 127.
If you use these values, the command will fail. You must first reassign the value in use to a different unassigned number, for example:
Specifies the voice coder rate of speech for a dial peer. Keywords and arguments are as follows:
modeframe_size--The iLBC operating frame mode that will be encapsulated in each packet. Valid entries are 20 (20ms frames for 15.2kbps bit rate) or 30 (30ms frames for 13.33 kbps bit rate). Default is 20.
bytespayload_size--Number of bytes in an RTP packet. For mode 20, valid values are 38 (default), 76, 114, 152, 190, and 228. For mode 30, valid values are 50(default), 100, 150, and 200.
Step 6
exit
Example:
Router(config-dial-peer)# exit
Exits the current mode.
Configuring an iLBC Codec in the Voice Class
When using multiple codecs, you must create a voice class in which you define a selection order for codecs; then, you can apply the voice class to VoIP dial peers. The voiceclasscodec global configuration command allows you to define the voice class that contains the codec selection order. Then, use the voice-classcodec dial-peer configuration command to apply the class to individual dial peers.
To configure an iLBC in the voice class for multiple-codec selection order, perform the following steps.
You can configure more than one voice class codec list for your network. Configure the codec lists and apply them to one or more dial peers based on which codecs (and the order) you want supported for the dial peers. Define a selection order if you want more than one codec supported for a given dial peer.
Specifies a list of preferred codecs to use on a dial peer. Keywords and arguments are as follows:
value--Order of preference, with 1 being the most preferred and 14 being the least preferred.
modeframe_size--The iLBC operating frame mode that will be encapsulated in each packet. Valid entries are 20 (20ms frames for 15.2kbps bit rate) or 30 (30ms frames for 13.33 kbps bit rate). Default is 20.
bytespayload_size--Number of bytes in an RTP packet. For mode 20, valid values are 38 (default), 76, 114, 152, 190, and 228. For mode 30, valid values are 50(default), 100, 150, and 200.
Step 5
exit
Example:
Router(config-voice-class)# exit
Exits the current mode.
Step 6
dial-peervoicetagvoip
Example:
Router(config)# dial-peer voice 16 voip
Enters dial-peer configuration mode for the specified VoIP dial peer.
Step 7
voice-classcodectag
Example:
Router(config-dial-peer)# voice-class codec 99
Assigns a previously configured codec selection preference list (the codec voice class that you defined in step 3) to the specified VoIP dial peer.
Note
The voice-classcodeccommand in dial-peer configuration mode contains a hyphen. The voiceclass command in global configuration mode does not contain a hyphen.
Step 8
exit
Example:
Router(config-dial-peer)# exit
Exits the current mode.
Verifying iLBC Support for SIP and H.323
You can use the following commands to check iLBC status:
showvoicecallsummary
showvoicecallstatus
showvoicedsmpstream
showcallactivevoice
showcallhistoryvoice
showvoicedspanditsextensions
showdial-peervoice
showvoicedspchanneloperational-status
Feature Information for iLBC Support for SIP and H.323
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature History Table entry for the Cisco Unified Border Element.
Table 1 Feature Information for iLBC Support for SIP and H.323
Feature Name
Releases
Feature Information
iLBC Support for SIP and H.323
12.2(11)T 12.2(15)T
The iLBC is a standard, high-complexity speech codec suitable for robust voice communication over IP. The iLBC has built-in error correction functionality that helps the codec perform in networks with high-packet loss. This codec is supported on both Session Initiation Protocol (SIP) and H.323.
The following commands were introduced or modified:
codecilbc,codecpreference, and
rtppayload-type.
Feature History Table entry for the Cisco Unified Border Element (Enterprise).
Table 2 Feature Information for iLBC Support for SIP and H.323
Feature Name
Releases
Feature Information
iLBC Support for SIP and H.323
Cisco IOS XE Release 2.5
The iLBC is a standard, high-complexity speech codec suitable for robust voice communication over IP. The iLBC has built-in error correction functionality that helps the codec perform in networks with high-packet loss. This codec is supported on both Session Initiation Protocol (SIP) and H.323.
The following commands were introduced or modified:
codecilbc,codecpreference, andrtppayload-type.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at
www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.