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Configuring Compression Parameters for VComp Bundles (CTP Menu)

This topic describes how to configure compression options for VComp bundles.

Before you begin:

  • Disable the bundle before you modify the bundle options.

To configure compression parameters for VComp bundles using the CTP Menu:

  1. From the Main Menu, select 1) Bundle Operations.
  2. Select 4) VCOMP.
  3. Select a bundle from the list.

    If you select an active bundle, you are prompted to disable the bundle before configuring it.

  4. Select 2) Config to configure the bundle.
  5. Select 4) Compression Options.
  6. Configure the options as described in Table 7.

Table 7: VComp Bundle Compression Parameter Settings in the CTP Menu

FieldFunctionYour Action


Specifies the pulse-code modulation (PCM) encoding standard used on the port PCM input to the VComp bundle.

When a VComp bundle is built with:

  • Analog voice interfaces, this configuration is applied on both the analog voice port and the voice compression module, so there are no compatibility issues.
  • T1/E1 channels, set companding to match the type of companding that is used for the external connecting equipment.

Generally, mu-law is used in the US, and a-law is used in Europe and elsewhere.

Select one:

  • 0) Transparent—Applies to T1/E1 ports only. Choose this option to transport lossless data in a VComp bundle (that is, for carrying a CCS signaling D channel).
  • 1) Mu-law—Generally used in the United States.
  • 2) A-law—Generally used in Europe and elsewhere.

Compression type

Specifies the level and type of voice compression performed on voice channels. See Calculating Resource Usage on Voice Compression Modules Overview for information about the voice compression module utilization and compression level for each compression type.

Select one:

  • G.729AB (8k)
  • G.711 (64k)

Echo Cancellation

Enables or disables echo cancellation.

When this option is enabled, 32 ms of local tail echo cancellation is performed on every bundle channel.

Select one:

  • YES
  • NO

Silence Detection

Enables or disables silence detection.

When this option is enabled and silence is detected on the channel, the network bandwidth used for that channel is reduced drastically. This behavior can create significant network bandwidth savings.

Select one:

  • YES
  • NO

Fax/Modem/STU Support

Enables or disables detection of fax and modem tones.

When enabled and fax or modem tones are detected on the line, compression is disabled and the channel reverts to PCM. Although enabling this attribute increases the amount of network bandwidth needed for that channel in the bundle for the duration of the fax or modem session, it succeeds in negotiation and transfer of fax and modem data at high speeds.

Select one:

  • YES
  • NO

Tone Relay

Enables or disables tone relay.

When enabled and tones are detected at the local end port, the tones are transported and regenerated at the remote end. This is an important option particularly for high compression levels, where tones may be distorted if they are compressed. The tone relay types supported are DTMF and MFR1.

Select one:

  • YES
  • NO

Secure Mode Support

When enabled and tones are detected on the line, the compression type for the bundle changes to G.711. After the fax session is over and the line is quiet for five seconds, the voice compression module switches the compression type back to its original configuration.

Select one:

  • YES
  • NO

Related Documentation

Modified: 2015-11-17