You answer a telephone call, and you realize that the caller is not looking for you but is looking for someone else in the house. Then you run to call the person. If you say there is a call for you, often the person will respond by asking who is on the phone. There you have it. Paul is writing this letter, he is telling the Colossians that the one writing to them is Christ Jesus, their Saviour.
1 Paul, an apostle of Christ Jesus by the will of God, and Timothy our brother,