Introduction

Overview

During voice communication between two terminal devices, one-way audio or no-way audio issues may occur. One-way audio means both parties can answer the call normally, but only one side can hear the other, while the other side cannot hear any sound. No-way audio means both parties can answer the call normally, but neither side can hear the other.

Applicable Models

All models of our products, including both industrial products and phone products.

Prerequisites

① Prepare one debugging PC with Wireshark installed, and connect it to the same LAN as the devices. Make sure the PC can communicate with the devices and with the SIP server.
② Confirm that the device power supply and network connection are normal, that the devices start up properly, and that they can access the network environment where they are deployed.

Connection Diagram for Devices and PC

Troubleshooting Method

When analyzing an audio issue, the first step is to identify the exact symptom of the one-way audio problem. In real-world applications, industrial intercom and access control devices often communicate with IP phones. Therefore, the following description uses the terms intercom and phone to represent the two call parties.

The Intercom Cannot Hear the Phone

When the issue is that the intercom cannot hear the phone, follow the steps below for troubleshooting:
1. Confirm which audio channel the phone is using: handset, speakerphone, or headset. If only the handset has been checked, switch to speakerphone and confirm whether audio is still unavailable. A common cause is that the handset cable is plugged into the headset port. In that case, the system uses the handset channel, but because the physical cable is connected to the headset port, audio cannot be picked up correctly.
2. Confirm whether the intercom shortcut key is configured as Speed Dial.
When the intercom calls the phone, the intercom shortcut key should be configured as speed dial:

Some users may accidentally configure it as Intercom instead.
3. If the intercom still cannot hear the phone regardless of whether the handset or speakerphone is used, follow the steps in section 2.3 to capture network packets simultaneously on the intercom, phone, and server, then send the capture files to technical support for analysis.

The Phone Cannot Hear the Intercom

1. Confirm whether the phone cannot hear the intercom only through the handset, or through both the handset and speakerphone. If only the handset has no audio, check whether the handset cable is plugged into the headset port.
2. If the phone uses a shortcut key to call the intercom, check whether the call type of the shortcut key is set to Speed Dial or Intercom. If it is set to Intercom, it can be changed to Speed Dial. If the shortcut key must use Intercom as the call type, then in the intercom settings, disable the parameter “Enable Intercom Mute“.

3. Follow the steps in section 2.3 to capture network packets simultaneously on the intercom, phone, and server, then send the files to technical support for analysis.

Neither Side Can Hear the Other During the Call

When neither party can hear the other during a call, the possible causes may include mismatched audio codecs on both ends or RTP transmission failure caused by network issues. In this case, the user needs to provide network packet captures to technical support for detailed analysis. The following is the packet capture procedure:
1. Log in to the WEB interface of device A, then go to “System” – “Auxiliary Tools” – “Web Capture”, and click “Start” to begin packet capture on device A.
Note: When capturing packets on the device, it is recommended to use the Chrome browser, as other browsers may have compatibility issues.

2. Repeat step 1 on device B to start packet capture on device B.
3. Start network packet capture on the server. For this part, consult the server vendor.
4. Place the call and answer it. After the call is connected, speak on both device A and device B, then hang up.
5. Stop packet capture on device A, device B, and the server respectively, then send all three packet capture files to technical support.