"We have our citizenship in heaven; it is from there that we eagerly await the coming of our Savior, the Lord Jesus Christ" (Phil 3:20). Therefore, before John saw the vision of the seven seals, seven trumpets, seven bowls, and seven plagues, he saw a vision of heaven. Heaven is the proper vantage point for understanding the book of Revelation, the future, the end of the world, and Jesus' final coming. Heaven is also the proper vantage point for understanding the past and present events on earth. When we, through our prayers (Rv 5:8), join in the heavenly worship at the throne of God, we begin to understand God, ourselves, and life. We sing with the angels and saints; "Holy, holy, holy, is the Lord God Almighty, He Who was, and Who is, and Who is to come!" (Rv 4:8)
Therefore, "set your heart on what pertains to higher realms where Christ is seated at God's right hand. Be intent on things above rather than on things of earth" (Col 3:1-2). "The trumpetlike voice" is saying: "Come up here and I will show you what must take place in time to come" (Rv 4:1).