How can I use 2G voice calls in Nexus 7 I have bought a Google Nexus 7 3G Tablet.

But, My country and area doesn't allow me to use 3G sims/Wi-Fi.

We have only 2G sims. When I insert the sim, I can connect to the Internet. I can send and receive SMS messages via "Go SMS Pro" application. 

But, I am unable to use voice call system which is available in any simple nokia / samsung java supported mobile.

Will my Nexus 7 allow me to send and receive Voice calls in 2G network? Because, to know sim balance we have to call on *XXX# or to know about data usage (Internet MB), we have to dial a number. Also, to call any phone number, we have to dial. So, what can I do to send and receive Calls like any simple mobile phone?
You can't do anything. The Nexus 7 3G doesn't support voice calls.