NethVoice CTI: Phone Island does not handle "Busy" state correctly when calling a busy extension

[mgarra]

Description:

When making a call to a busy extension through the Phone Island, the busy state is not handled correctly. Instead of receiving a busy signal and the appropriate tone, the call is simply closed without any feedback or indication of the reason.

Steps to Reproduce:

1. Create two extensions (for example, 201 and 202), or use existing ones.
2. Ensure that extension 202 has at least the "Base" profile assigned, and that Web Phone and Desktop Phone are enabled.
3. From extension 201, call the echo test number *43.
4. While extension 201 is busy, attempt to call it again from extension 202 using NethCTI.
5. Observe the behavior when a call is made to the busy extension.
6. While extension 201 is busy, attempt to call it again from extension 202 using NethLink.
7. Observe the behavior when a call is made to the busy extension.

Expected Behavior:

When calling a busy extension, the user should hear the typical busy tone and see a message or indication that the callee is currently busy.

Actual Behavior:

The call ends without any message or busy tone.

From the call dialog, it’s visible that a 486 Busy Here response is correctly received, but it appears to be ignored by the Phone Island.

As a result, the user is left without any information about the call status.

Affected Platforms:

The issue occurs both on NethCTI and NethLink.

Physical phones and the mobile app handle this scenario correctly, properly interpreting the 486 Busy Here response.

Screenshot:

[tonyco97]

Testing releases:

• https://github.com/nethesis/ns8-nethvoice/releases/tag/1.4.5-testing.6
• feat: nethcti-middleware nethlink#72 (comment)