If you can't hear the audio when playing back a recording, check these things:
1. Make sure you don't have your iPhone set to silence/vibrate. 99% of the time, this is the issue our customers have. We do this so they don't inadvertently disturb a meeting.
2. Make sure to turn up the volume on your iPod / iPhone.
3. Use your headset if it's plugged in, or unplug your headset to use the speakers built into your iPhone.
4. Remember that you must use an external mic on a 1st and 2nd gen iPod Touch. The 2nd gen iPod Touch can use the Apple earbuds with integrated microphone. The 1st gen iPod Touch must use a mic that connects via the docking port (not the headphone jack) and must have the 2.2 operating system installed. Note that recent 3.0+ OS updates from Apple has disabled the 1st Gen iPod Touch's ability to use recording apps. We can not control this.
5. Reset your iPhone. This is done by going to "Settings", then "General", then "Reset", then "Reset All Settings". However, after you do this, you will need to redo all your settings such as the connection to your network, ring tone, etc.