The standard alarm contracts that I offer the trade contain a UCC
provision.  This permits the alarm company to secure the subscriber's
obligation under the contract by placing a lien on the alarm equipment.  The
provision can be expanded to include all assets of the subscriber in the case
of commercial accounts.
       All states have the Uniform Commercial Code (except perhaps Louisiana).
This is the statute that creates liens on personal property.  Filing the UCC-1
in the designated governmental office creates the lien.
       Once the lien is filed it turns you into a secured creditor, rather than
an unsecured creditor.  Your subscriber will not be able to sell its liened
assets free of the lien.  If the subscriber files bankruptcy, you will be a
secured creditor rather than unsecured.
       Though the contract permits you to file the UCC-1 as soon as the
contract is signed you should probably wait until you think the subscriber may
be in financial trouble and going to default on the contract.  However, if the
subscriber files bankruptcy within 90 days of the UCC-1 filing the lien can be
set aside as a preference, making you unsecured again.
       The UCC-1 can be effective in protecting your receivable from the
subscriber.