I hear only one side when I playback a call.

First of all check, if your headphones play correctly audio in stereo format.

By default MiaRec saves files in stereo format. One call party is recorded in left audio channel and other party is recorded in right channel.

Try to play the file on another computer and on different headphones.

Some software firewalls may block one side of conversation. Try to disable firewall on your computer and make a test call again.

If the problem still exitsts, please, send us WAV/MP3 file for investigation to support@duxoft.com.