asterisk-dahdi-13.9.1-1.fc25.1.x86_64 cannot be installed in Fedora 26 because is requires "libtonezone.so.2.0()(64bit)" that's not in the repository.
The same problem is in Fedora 25 and problem is probably missing dahdi-tools package.
*** This bug has been marked as a duplicate of bug 1387525 ***