I can't hear the person I'm talking to, or vice versa. How can I fix this problem?
This type of issue is usually caused by a hardware malfunction or an incorrect network configuration of the firewall or devices.
Below, we list the possible causes, along with steps you can take to troubleshoot the issue—and in most cases, even resolve it yourself.
Cause 1: Ports are blocked
With Voice over IP, or “VoIP” for short, data packets must be able to travel unimpeded between the two call participants. This RTP packet traffic occurs in the port range between 10,000 and 50,000. Please check whether the relevant ports are properly opened and then try again. Our Easybell app uses the range from 10,000 to 20,000. So if you’re having problems with our app, you should check that the range from 10,000 to 50,000 is open.
For more information, see our article “Configuring the Firewall for Easybell Telephony.”
Cause 2: Incompatible Codecs
Codecs are used to convert audio signals (i.e., speech) into data packets. There are different codecs with different characteristics. For voice transmission to work properly, both parties in the call must support the same codecs. For example, if one party—such as your device or phone system—has only enabled the G.722 codec (HD telephony) and the other party does not support this codec, successful negotiation will not occur and no voice will be transmitted.
To ensure successful voice transmission on all devices, it is recommended to enable PCMA and PCMU. In any case, the G.711A (PCMA) codec must be configured. This codec represents the minimum standard agreed upon in Europe. By using G.711A, every participant in a call should be able to complete it without any problems. This is particularly important for emergency calls.
Isolating the Cause of the Error
You can use a simple softphone test on the affected network to determine whether the issue is caused by a faulty network configuration or a misconfiguration of the devices. It is important that you temporarily disable your phone system for the test. If the issue can be reproduced, check your network configuration. If the issue cannot be reproduced, please check the RTP settings of your VoIP hardware.
Alternatively, you can use a TCP dump to identify the faulty gateway in your network. If you can pinpoint the issue on our end, please send the generated log file to our 2nd-level support team for review.
If the issue can be reproduced with softphones on the same network, please check your firewall. If this resolves the issue, please check the settings on your device.