I am just using this app for the first time. I am not getting any volume. I am using the built-in camera on a 13" Macbook running Snow Leopard.
The volume settings on my iphone are all on, and the volume is at its loudest.
On the laptop I have checked the microphone settings and they are at maximum.
I bought this solely for the purpose of being able to hear my dog during the day (he has some separation anxiety and we just moved into a new place).