An echo effect can occur when one or more participants in the voice conference are using their regular computer speakers rather than headphones. To ensure the best possible audio quality for everyone, ask everyone to use headphones or a headset for the voice conference.
Alternatively, if there is a lot of background noise or an echo effect coming from one of your participants, you can mute that select participant (or multiple participants) in your VoIP call. This will prevent an echo effect from your participants while you’re speaking.
Another way to prevent any echo effects, is to ensure that you are using the "echo cancellation" feature. First open your VoIP settings by clicking on the settings cog icon during a VoIP call - see the grey arrow below.
The following window will then open on your screen:
Make sure that "Echo Cancellation" is checked. You can also access the "Microphone Sensitivity" from here. If one of your participants has an overly sensitive microphone that is transmitting a lot of noise from their side, you can ask them to open their VoIP settings (as described above) and to reduce their Microphone Sensitivity.