If you have been trying to call campgrounds in Alaska (or northern Canada) to make reservations for your trip this summer, they likely have been closed. After all, it is winter up there. They rarely have someone answering the phone in winter. Generally, you can leave a message but they may not check on those messages frequently. I’ve waited two weeks for a return call. A number of campgrounds will have contact pages on their website for use especially in winter. Try them.
Many campgrounds open their offices (but not necessarily the actual campground) starting May 1st (but some are later than that, too). That is, they MAY actually answer the phone!
So, if you have tried to call but had no luck, try now.