Fall practice has started. Coaches are busy trying to figure out what they have as far as returnees, incoming freshmen, incoming transfers, etc. Unless your son is a top level kid that they are really really after, speaking to him as a 2024 isn't high on their priority list right now. I'd probably shoot the coach an email.....say "coach, I tried to reach you by phone, but I'm sure things are busy with fall practice starting up....is there another that works better for me to contact you?" Coaches read emails because they can do that when they have a couple minutes free. It's much easier to do that then take a phone call when they may be in the middle of something. If you don't get at least some kind of acknowledgement/return email, you can pretty much assume that there isn't much interest at this point.