first of all: I plugged USB modem to my Computer and I want to communicate that usb modem using C# Code as follows:-
first connect to USB then access its services like internet and checking balance using Code.
if any Idea please give me ENGs

That's a big project. And not how one would usually go about this. I can't guess if you installed the drivers and set the PC up to dial up your dial up internet service but your post as-is would be something of a many month long project if you were to say have just Windows (no drivers for the modem) and wanted code to do all that!

rproffitt it is not big Project
I am using USB for USSD Modem and I want C# code to Communicate that modem Can you give any idea or code concerns with it

I know what an USB Modem is. Many enumerate to a serial port and then we would install SLIP or such to get ready to dial up the Internet.

But you want to handle all that yourself which is a huge project. I'm reading your top post and it's something you would tackle over a year.

Now if you wanted to just setup up your Internet connection the normal way you would do that then many curl some web page with the data you want but you are asking for so much more. You are asking to handle all the dial up, IP stack, drivers, all in your code. That's a huge undertaking.

My bet is what you wrote at your top post is not what you wanted to do.