Am I able to talk on a Blackberry 8700c while it is tethered for
internet use to my laptop?

I would imagine not since the internet will be taking up the bandwidth
normally used for voice however the simplist way to tell is connect to
the internet and phone your mobile.

While this is the obvious way to tell, I desire to know the answer
before I purchase a Blackberry; if this is not a capability, I will
not purchase one.