EVO 4G phone voice not coming through, calls not going to voicemail.

I  just got my HTC EVO 4G a week or so ago and got it activated on the service relatively quickly after receiving it.  I was disappointed to see that the EVO 4G was still a android gingerbread device, but can live with that - if it functions as advertised.  

When sending text messages everything seems to work fine. I sent texts to several people and received some back with no issues.

When I tried making phone calls - that's when issues started. The first phone call worked fine. I was on WiFi and was able to have a normal conversation with decent call quality.

On the second phone call I called my wife while i was out running errands. I was on 4G, but when she picked up, i could hear her, but she couldn't hear me.  When I double checked the mic volume it was fine, so I'm not sure why she couldn't hear me.  Our home phone is a VOIP Ooma phone - not sure if that matters.

On the third call I tried calling my old Virgin Mobile prepaid cell phone from the Freedom Phone, while on 4G connection. The call connected and I was able to speak and be heard no problem, although the call quality didn't sound too great and there was a bit of delay.

Finally I called my cell phone and let it ring so I could leave a voicemail while on 4G to hear how it sounded - and the Virgin Mobile phone never goes to voicemail. It just rings and rings and then stops ringing ending the call. I then called that same Virgin Mobile phone from our home phone and it goes through just fine to voicemail.  I tried this about 4 times to make sure it wasn't just a hiccup or bad reception.  It never did go to voicemail with the freedom phone. Has anyone else experienced strange issues like this?  

If you have had issues like this - were you able to fix them?