Can someone explain this to me?

The memo of the July 25 phone call is about 10 minutes of a 30 minute call. What about the rest of the call? Is there a recording of the whole call somewhere? In the clouds? Can it not be retrieved? I have watched, listened, read, etc. everything I can and no one addresses this. The call was put on a super secret server, password protected. There has to be a “hard copy” of it. I realize this impeachment is so much more than this one call but I would love if someone can enlighten me on this. We are talking about history here (i.e. Nixon’s 18 minute tape) and I cannot believe the whole call cannot be released. Of course, it will probably go to the SCOTUS like everything else. Any explanations will be appreciated.