调用函数而不引用对象

#中的菜鸟，所以我在尝试使用系统事件参数调用C#中的函数时遇到问题。我知道问题不在于系统事件参数，但是我应该调用这种类型的函数的正确方法是什么？

错误 1：非静态字段需要对象引用， 方法或属性 'ConsoleApplication3.Program.Reject_call(对象， System.EventArgs('

错误 2：非静态字段需要对象引用， 方法或属性 'ConsoleApplication3.Program.Accept_call(对象， System.EventArgs('

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Lync.Model;
using Microsoft.Lync.Model.Conversation;
using Microsoft.Lync.Model.Conversation.AudioVideo;
namespace ConsoleApplication3
{
    class Program
    {
    //holds the Lync client instance
    private static LyncClient _client;
    //holds the reference to the conversation associated with this window
    private Conversation conversation;
    //self participant's AvModality
    private AVModality avModality;
    private static void Main(string[] args)
    {
        //Obtains the lync client instance
        _client = LyncClient.GetClient();
        consoleInputReadRoutine();
        _client.ConversationManager.ConversationAdded += ConversationManager_ConversationAdded;
        _client.ConversationManager.ConversationRemoved += ConversationManager_ConversationRemoved;
        Console.ReadLine();
    }
    static void ConversationManager_ConversationAdded(object sender, ConversationManagerEventArgs e)
    {
        e.Conversation.Modalities[ModalityTypes.AudioVideo].ModalityStateChanged += Program_ModalityStateChanged;
    }
    static void Program_ModalityStateChanged(object sender, ModalityStateChangedEventArgs e)
    {
        Console.WriteLine("Modality state changed " + String.Format("{0} => {1}", e.OldState, e.NewState));
    }
    static void consoleInputReadRoutine()
    {
        bool done = false;
        while(!done){
            string input = Console.ReadLine(); // Get string from user
            Console.WriteLine("user input {0}'n", input);
            // Set exit condition.
            if(String.Compare(input, "exit") == 0){
                done = true;
            }
            else if (String.Compare(input, "reject") == 0)
            {
                //Do a reject call.
                Reject_call(null, new EventArgs());
            }
            else if(String.Compare(input, "answerswer") == 0)
            {
                //Do a answer call.
                Accept_call(null, new EventArgs());
            }
        }
    }
    // Accepts an incoming call: AvModality.Accept()
    private void Accept_call(object sender, EventArgs e)
    {
        //accepts an incoming invite (syncronous operation)
        avModality.Accept();
    }
    // Rejects an incoming call: AvModality.Reject()
    private void Reject_call(object sender, EventArgs e)
    {
        //rejects an incoming invite (which will disconnect the call)
        //the ModalityDisconnectReason may be used to specify a reason to the caller side
        //the reason may be shown on the Lync client conversation window
        avModality.Reject(ModalityDisconnectReason.Decline);
    }
    static void ConversationManager_ConversationRemoved(object sender, ConversationManagerEventArgs e)
    {
        //Exit out of program if you wish after conversation is removed.
    }
    }
}