NethVoice: add new Ringtone: mute tone

[tonyco97]

Description

Some customers use NethLink only for Click-to-Call, while incoming calls are handled by a physical desk phone (for example Yealink).

In this scenario, when an incoming call arrives, Phone Island always plays a ringtone, even if the user does not intend to answer calls from the softphone.

Currently, there is no supported way to mute only the ringtone inside the application.

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Why this feature is needed

In many real office environments:

• Users answer calls on a desk phone
• NethLink is used only to start outbound calls
• The ringtone generated by Phone Island becomes unnecessary and disruptive

The only available workarounds today are:

• Muting the entire application from the OS audio mixer
• Replacing ringtone files manually
• Disabling system-level notifications

These solutions are:

• Not portable
• Not officially supported
• Not testable
• Not manageable by support

A built-in silent ringtone would provide a clean and supported solution.

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Purpose of the feature

Provide an official way to mute incoming call ringtone inside Phone Island without:

• Muting the entire application
• Modifying application files
• Using OS-level workarounds

This improves usability, supportability and configuration flexibility.

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Proposed solution

Add a new ringtone option:

Silent

This ringtone should:

• Be bundled inside the repository
• Be selectable like any other ringtone
• Contain no audio (empty WAV or MP3 file)

When selected, incoming calls should not produce any sound, while keeping all other application audio functional.

[federicoballarini]

Disabling Windows notifications doesn't seem to be a workaround, as Phone Island opens anyway.