Echo is typically caused something that is transmitted from the phone being used as it is received from the microphone/speakers being used. For your Plantronics Bluetooth headset try making sure that you have the Plantronics hub installed (and update the firmware on the device) to make sure it is working to the best of its ability. Another step would be to lower the volume of the speakers in case the microphone is picking up the audio coming from the speaker(s). Also, check the settings for any echo/reverb detection. This is what we see typically resolve the issues people encounter, though you may want to reach out to Plantronics and see if they have any other tips as well.