Dear Michelle I am familiar with the optima XM and as many other alarms, the tamper circuit is N/C (normally closed) just a link between two terminals. In my opinion tamper circuits are unnecessary in domestic installations whoever you let in your house isn’t going to tamper with the wiring or detectors, if any things is wrong with the wiring or detectors the panel will show this anyway. As for the bell box unless your system is over 20 years old then the bell will still ring and you cant stop it even if you cut its cable. Ask your friend who replaced the bell box micro switch to remove the alarm panel cover, on the connecter strip usually left hand side you should see tamper printed on the circuit board, put a link between the two terminals this will disable the tamper circuit other than the alarm panel cover… If this fails the panel is probably faulty. Good luck.
Timbo
February 2008