It sounds like you are trying to find living people in Family Tree by their ID number. The system will not allow you to do that for privacy reasons. Since you said you were talking with your father on the phone, we know he is alive. If you do a Find by ID for the ID he has in his own tree, it will tell you no results found.
So what you need to do is create your own ID for your father in your tree. Then if his father is deceased you will be able to add him to your tree as your father's father using the ID your father sees in his tree. While we all have to have a different ID for living people, we all should have the same ID for deceased people. When you do that, that line in your tree will look exactly like that line in your father's tree.
This article explains how "private spaces" work in Family Tree.
We hope this helps.
Also, I type in an I.D. which I know is accurate and the system gives me a message saying that it's unable to find,....Yet me father can be on the phone with me using the same accurate I.D.