Silent calls generated by AI agent

[tzorzo]

Hi there,

We are currently experiencing instances of silent calls generated by our AI agent.

More specifically, this happens randomly and without any apparent reason: the agent does not generate any audio during the call.

In the call recordings, I can see a valid call record between the customer’s phone number and the AI agent’s number (so I would rule out routing issues), but only the customer’s audio is present. The customer can be heard saying, “Hello, is anyone there?”, while no audio is generated by the agent.

From the "3CXAI.log" I can only notice these logs:
2026-01-12 17:32:27.645|WARNING|{'call': 130, 'dir': 'pbx'} Endpoint PC lost connection; forcing idle & closing bridge
2026-01-12 17:32:27.646|WARNING|{'call': 130} force_idle: recovering to idle
2026-01-13 09:00:36.923|WARNING|{'call': 131, 'dir': 'pbx'} Endpoint PC lost connection; forcing idle & closing bridge
2026-01-13 09:00:36.925|WARNING|{'call': 131} force_idle: recovering to idle
2026-01-13 09:04:02.633|WARNING|{'call': 132, 'dir': 'pbx'} Endpoint PC lost connection; forcing idle & closing bridge
2026-01-13 09:28:09.254|WARNING|{'call': 133, 'dir': 'pbx'} Endpoint PC lost connection; forcing idle & closing bridge
2026-01-13 10:04:12.042|WARNING|{'call': 134, 'dir': 'pbx'} Endpoint PC lost connection; forcing idle & closing bridge

Versione 20.0 Update 8 (Build 1078 Beta) on-promise installation (Debian)

 

[KyriacosS_3CX]

Hello,

Please put the system logging in Verbose mode and let's see if there is more information, you can leave it capturing for a few days until the issue happens again. A wireshark capture might also be informative, but that would not be easy to time so it captures the issue.

Is the internet connection at your location reliable, and with enough bandwidth for voice and other traffic?

 

[tzorzo]

Hello, thank you for your reply.
Please find attached the relevant portion of the 3CXAI.log, captured in verbose mode during a silent call event.

My internet connection seems to be ok (speedtest from the 3cx vm):

 

[nikolascx]

Hi @tzorzo

Thanks for reporting. We see a potential problem

10:09:02 - Call connects successfully to OpenAI's realtime API
10:09:03 - OpenAI connection established (openai_pc.state > connected)
10:09:03 - Data channel opens (oai-dc > OPEN)
10:09:12 - Only 9 seconds later, PBX closes the connection (PBX call closed, close scheduled)

As a result the AI Agent received 0 seconds of audio input, "hearing" silence so it generated 0 responses.

'accumulated_input_audio_tokens': 0,
'realtime': {
'input_audio_tokens': 0,
'output_audio_tokens': 0,
'responses_count': 0
}

Potential issues / things to try / look out for....

• Can you wait - do not hang up. We want to see if ever you get an answer from OpenAI. So stay for 30+ seconds.
• If it works, you confirmed it is a timing / load issue.
• How is your network? Are you behind an exhausted firewall?
• Any competing UDP traffic affecting port availability?
• NAT/firewall behavior can be inconsistent
• OpenAI API key limit - check your spending cap / rate limits etc. Maybe you reached a limit and it gets queued.

Keep us posted - this should not happen.