Adobe Connect Pro supports both Teleconferencing (using and audio bridge with telephony) and Voice over Internet Protocol (VoIP).
To get the best results when using VoIP it is recommended those connecting use a headset with microphone. When a microphone is used with speakers (as opposed to headphones), there is a greater chance of feedback and echo. The exception is when the VoIP session is being used for a presentation where audio broadcast is one-way. The presenter uses a microphone and the room or computer speakers are muted. This prevents speaker sound being captured by the mic.
Another method of configuring VoIP is to have echo-canceling enabled and set the conference to allow only one speaker at a time. To do this, configure the "Talk" button to allow one speaker only - "Voice on - One Speaker".