Caller on other end hears an echo during a call (Android)

We have observed certain phone models (some Samsung and LG models, including Nexus 4) exhibit poor echo cancellation functionality with Voip apps, including Fongo.  This will be apparent if you are on a call with someone and they can hear their own voice echo on their end of the call.  In Fongo 3.0+ we have added a couple of options to help alleviate the issue.  We recommend enabling the Use Alternate Echo Canceller options and/or adjusting the default Microphone Volume, you may have to experiment with both options to find an optimal median. 

These two settings are found in: Account > Settings > Troubleshooting