how can I make a call to *190*phone number# in c#?

PhoneCallTask phoneCallTask = new PhoneCallTask();
phoneCallTask.PhoneNumber = "Phone Number Here";
phoneCallTask.DisplayName = "Display Name HERE";   
phoneCallTask.Show();

Try to do it with a PhoneCallTask, this will show in your Call screen the number and the name, the only thing that you have to do then is to hit the Call button.

Best regards.