1. #Determine your current runlevel using the <code>runlevel </code> command. 2. #Change to the appropriate startup directory in a terminal window. For example, if your runlevel is 4, change to <code>/etc/rc.d/rc4.d</code> 3. Record #Observe the names of the symbolic links in that directory. 4. #Where do the links link to?#Run the menu option <code>System>Administration>Services</code>. You will then see the Service Configuration screen. 5. #Find the <code>isdn </code> service and select customize from the tool bar. and deselect the checkbox for your runlevel from step 1. Quit the app. 6. #Return to the terminal window you used in Step 2. Get a listing of the symbolic links in the startup directory. Is it any different from what you recorded in Step 3observed previously? 7. #Using the Service Configuration screen, reenable re-enable the <code>isdn </code> service. 8. Repeat step 6#Check the symbolic links again. What has changed this time? 9. #Run this command:#*<code>chkconfig isdn off</code>#Now what has changed in the directory?#Run this command:#*<code>chkconfig isdn on</code>#Now what has changed?#Run the command:#*<code>chkconfig --list</code>