no sound fro Jabra BT530 when connected to a call

I just purchased a Jabra BT530 and I connected it to my iPhone 3G (latest software update). I CAN hear sounds from the headset when I dial a number, adjust the volume and power on/off and I can even hear music when I play iTunes. I CANNOT, however, hear sounds when I connect to a call. The person on the other end can hear me through the headset, but I can't hear them (so the mic is working, but the earpiece doesn't seem to be working in "call mode"). I played around with the volume and speaker settings and disconnected and reconnected the headset with no luck. I just thought I'd check these discussion to see if anyone had a similar problem and resolved it before I return the headset. Any ideas/suggestions?

Thanks in advance.