NethVoice: Add audio initialization extension in Asterisk dialplan

[edospadoni]

Description:

A dedicated extension number needs to be added to the Asterisk dialplan to allow audio initialization for Phone Island, CTI and Desktop Phone clients. This extension will be used to test and initialize the audio subsystem before making actual calls.

Expected behavior:

1. User dials the initialization extension number (e.g., *17)
2. Call is answered automatically
3. After 1-2 seconds of silence, a beep is played
4. Call hangs up automatically

Technical implementation:

The extension should be added to /etc/asterisk/extensions_custom.conf:

[from-internal-custom]

exten => 4321,1,Answer
exten => 4321,n,Playback(beep&silence/2)
exten => 4321,n,Hangup

Use cases:

• Audio device testing and initialization
• Microphone/speaker verification
• Audio subsystem warm-up for WebRTC clients

Notes:

• Should work with both WebRTC and Desktop Phone devices
• Minimal latency and immediate response required