I got my 8700c yesterday, just finished posting about it.
To be honest, I haven't tried using it much as a phone withOUT my jabra250 bluetooth. Come to think of it, I haven't tried it at all.
However, with the jabra250, I was just posting it was nearly perfect audio. It's hard to be sure I'm judging something "real", and not just giddy with new device happiness, though.
On my 7100 with the bluetooth, a few of my friends would tell me the connection didn't sound all that hot. I called all of my them with the 8700c and the jabra, and they said it sounded like a remarkable improvement. I did these test calls from my call, doing about 60, with both the windows closed/radio off .. and the radio up and window down
I'll try it out today with the "calculator the face" method.
Now .. how about ringtones? ;)