If you run make install, properly, on a RedHat family system, including CentOS, it will copy dahdi.init to /etc/init.d/dahdi and then run chkconfig to link it in to the run level directories.
If you run make install, properly, on a RedHat family system, including CentOS, it will copy dahdi.init to /etc/init.d/dahdi and then run chkconfig to link it in to the run level directories.