3.1.  Global Tone Detection (GTD) Tone Considerations

NOTE:

The information in this section is applicable to Springware boards only.

Global Call will delete all tones and load internally required tones (used for call progress) under either of the following circumstances:

• If there is a voice device attached to the network device during gc_OpenEx( )
• When gc_Attach( ) or gc_AttachResource( ) is called, if at least one of the following statements is true:
  • This is the first time the voice resource is being attached to a network device opened in the PDK library (either implicitly via gc_OpenEx( ), or explicitly via gc_Attach( ) or gc_AttachResource( )).
  • Downloading of tones is enabled (gc_SetParm(ldev, GCPR_LOADTONES, GCPV_ENABLE)).

If Global Call deleted all tones during gc_OpenEx( ), gc_Attach( ), or gc_AttachResource( ) as described above, then the application must reload any tones that it has loaded. It is recommended that the application not download tones for a voice device prior to calling gc_OpenEx( ) if the voice device is specified in the gc_OpenEx( ), as the tones will be deleted. Similar considerations apply to gc_Attach( ) and gc_AttachResource( ).

It is the application's responsibility to ensure that the internally required tones are available to the protocol during call setup. This can be done by either:

• Never deleting all tones, or
• If the application has deleted all tones while the voice resource is not attached, enabling downloading of tones

CAUTION

The application must not delete all tones while the voice resource is attached.

In any case, the application may not delete internally required tones during call setup.

NOTE:

For PDK and ICAPI protocols, the tone IDs for any additional tones that must be redefined after calling gc_Attach( ) or gc_AttachResource( ) cannot be in the range from 101 to 189.

The overhead of downloading tones is expensive. Therefore, for any application that calls gc_Attach( ) or gc_AttachResource( ) several times on the same device (for example, when resource sharing), this overhead can be avoided by calling gc_SetParm(ldev, GCPR_LOADTONES, GCPV_DISABLE). This gc_SetParm( ) function should be called after the first call to the gc_Attach( ) or gc_AttachResource( ) function, or after the call to the gc_OpenEx( ) function if the voice device is specified in gc_OpenEx( ). It is then the application's responsibility not to delete all tones on the voice device.

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