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The present invention relates to real estate lockboxes. Lockboxes are used
in the real estate industry to contain the keys of houses listed for sale.
Prior art lockboxes have primarily been mechanical devices which allow
access to a secure compartment by use of a conventional key. Such
lockboxes and keys, however, have had certain disadvantages.
One disadvantage has been the inability of the lockbox to store information
relating to the time and date the lockbox is accessed, together with the
identity of the accessing real estate agent. Another disadvantage has been
the inability to coordinate large numbers of lockboxes and keys into an
integrated system that allows a supervising real estate board to monitor
listing activity and to exercise management control over its lockboxes and
keys.
Accordingly, a need remains for an improved real estate lockbox, key and
lockbox system.
SUMMARY OF THE INVENTION
One feature of the present invention is the provision of a lockbox that
records information relating to the time and date the lockbox is accessed,
together with the identity of the accessing real estate agent.
Another feature of the invention is the provision of a lockbox system that
allows the supervising real estate board to monitor listing activity and
to exercise management control over its lockboxes and keys.
Another feature of the invention is the provision of a lockbox that cannot
be opened during certain predetermined periods during which a resident
homeowner may not welcome visitors.
Yet another feature of the invention is an arrangement whereby certain
lockbox keys become inoperative after a certain period of time.
Still another feature of the invention is an arrangement whereby the
lockbox can be made inoperative to all real estate agents.
Another feature of the invention is an arrangement whereby the lockbox can
be automatically disabled after the shackle holding it in place is
released.
Still another feature of the invention is an arrangement whereby software
used with the system is protected against misappropriation.
Still another feature of the invention is an arrangement whereby access
data stored in the lockbox can be retrieved by a portable unit.
Another feature of the invention is an arrangement whereby a lockbox can be
reprogrammed over telephone lines.
Yet another feature of the invention is an arrangement whereby the access
log maintained in the lockbox can be marked to enable retrieval of
selected portions of the log.
Another feature of the invention is an arrangement whereby codes needed to
access the lockbox can be entered on a key before the key is engaged with
the lock.
Still another feature of the invention is an arrangement whereby
information relating to recent attempts to operate keys and lockboxes are
stored in memories within such units to facilitate resolution of anomalous
key and lockbox behavior.
Still another feature of the invention is an arrangement whereby certain
real estate agents can be prevented from accessing certain lockboxes.
Yet another feature of the invention is the provision of circuitry whereby
the lockbox consumes negligible power until a key is coupled thereto.
Still another feature of the invention is an arrangement whereby a listing
agent can maintain control over which other agents show a listed house.
Yet another feature of the invention is an arrangement whereby agents from
several different real estate boards can obtain access to a real estate
lockbox.
Still another feature of the invention is a provision whereby access
information retrieved by the portable unit can be coupled to a central
data storage unit over telephone lines.
Still another feature of the invention is the provision of a lockbox
database containing data on all lockboxes and keys owned by a real estate
board.
The foregoing and additional features and advantages of the present
invention will be more readily apparent from the following detailed
description of a preferred embodiment thereof, which precedes with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of a Level One system, with a component from a Level
Two system shown in dashed lines.
FIG. 2 is a schematic block diagram of an agent key used in the system of
FIG. 1.
FIG. 3 is a schematic block diagram of a lockbox used in the system of FIG.
1.
FIG. 4 is a schematic block diagram of a reader key used in the system of
FIG. 1.
FIG. 5 is a schematic block diagram of a programmer key used in the system
of FIG. 1.
FIG. 6 is a schematic block diagram of a data communicator unit used in the
system of FIG. 1.
FIG. 7 is a schematic block diagram of a pod used in an enhanced version of
the system of FIG. 1.
FIG. 8 is a diagram of a computer and trunk interface unit used in another
enhanced version of the system of FIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT LEVEL ONE SYSTEM
The Level One, or basic, system 10, shown in FIG. 1, includes one or more
lockboxes 12, agent keys 14, reader keys 16, programmer keys 18 and data
communicator units 20. (A "pod" 102 used in the Level Two system is shown
in dashed lines.) Lockbox 12 contains the door key to the listed dwelling
and is mounted securely on or near the dwelling. Agent key 14 is used by
real estate agents to open the lockbox and gain access to the key
contained therein. Reader key 16 and programmer key 18 are used to read
data from, and load instructions into lockbox 12, respectively. Data
communicator unit 20 is used to recover the data read by reader key 16 and
to load instructions into programmer key 18. These elements are described
in more detail below.
Lockbox 12 includes a secure enclosure 13 designed to hold house keys,
business cards, written messages and the like. The lockbox is securely
attached to the listed house or other fixed object by a shackle 22 or by
screws (not shown). Shackle 22 in most instances attaches the lockbox to a
door knob, water spigot or porch guardrail. Upon a proper exchange of
signals between lockbox 12 and an agent key 14, as described below, the
lockbox compartment opens, allowing access to the house key and other
materials stored inside.
In the preferred embodiment, the exchange of signals comprises a three-way
handshake. First, the agent key 14 sends a first control signal (a) to
lockbox 12 which includes a key identifier code identifying the agent, the
agency, the real estate board and the agent key serial number. If the
lockbox recognizes the first control signal as being property authorized,
it then responds by sending a second control signal (b) back to the agent
key identifying the lockbox. Upon receiving the second signal from the
lockbox, the agent key determines whether the lockbox is one to which it
is authorized access. If such a determination is favorable, the key sends
a third, unlocking signal (c) back to the lockbox. The lockbox storage
compartment 13 then opens.
All communications with lockbox 12 are effected optoelectronically. Lockbox
12 is equipped with an optoelectronic communications port 24 which
includes a transmitting light emitting diode (LED) 26 and a receiving
photodetector 28. All keys and other units which communicate with lockbox
12 have a corresponding optoelectronic communications port comprising a
reciprocal photodetctor and LED pair.
The agent key 14 has length and width dimensions comparable to a credit
card, and a thickness of approximately a quarter inch. The circuitry of
agent key 14 is shown in FIG. 2 in block diagram form. A 16-key keypad or
other switch mechanism 30 is connected to a central processing unit (CPU)
32, which is powered by a battery 34. The user energizes the key by
pushing an "ON" button on keypad 30. A "STATUS" L.E.D. 36 then begins to
flash, indicating that agent-key 14 is energized. (Alternatively, an
audible tone generator, not shown, can be substituted for the L.E.D. 36.)
The user then has ten seconds within which to enter a four digit password
on keypad 30. If no password code is entered, a timer 44 in agent key 14
causes the key to become deenergized again. If the four digit sequence
matches the sequence stored in an agent key RAM memory 30, the key becomes
"armed." After the key is "armed," the user can press an "OPEN" button on
keypad 30 which causes CPU 32 to send the above-described first control
signal (a) to lockbox 12 using a transmitting L.E.D. on its optoelectronic
communications port 42. Agent key optoelectronic communications port 42
also includes a receiving photodetector 46).
If an improper four digit password is entered on touch pad 30, agent key 14
will not arm and will not send a signal to lockbox 12. The user can then
start over and enter the proper password. If, after five tries, the proper
password is still not entered by the user, the CPU 32 is configured so
that agent key 14 will deactivate itself for a ten minute period and will
not allow any further codes to be entered.
Agent key 14 is initially activated by a programming routine that is run on
data communicator 20. This routine loads a variety of information, and
enables a number of functions, into the agent key. The information loaded
includes the agent, agency, board, password, and key expiration date
(discussed below). Functions enabled may include shackle release
(discussed below). After its initial activation, the agent key will not
require further programming, except for periodic rejuvenation (also
discussed below).
FIG. 3 is a block diagram showing circuitry of lockbox 12. Photodetector 28
of lockbox optoelectronic communications port 24 receives the first
control signal (a) from the transmitting LED 40 of the agent key 14. It
then decodes this signal and feeds it to a lockbox CPU 48. (CPU 48 and
other lockbox circuitry is powered by an internal battery 50.) If the CPU
recognizes the first control signal as corresponding to an authorized key,
lockbox 12 returns the second control signal (b) to agent key 14 using
transmitting LED 26 of optoelectronic communications port 24. If CPU 48
does not recognize the key identifier code sent from agent key 14 in first
signal (a), or determines that the key identifier code is otherwise
invalid, lockbox 12 will not respond with the second signal (b).
The second signal (b) sent by lockbox 12 to agent key 14 includes an
assignment code identifying the board, agency and agent which listed the
house. When agent key 14 receives this assignment code, its internal CPU
32 scans a list of authorized codes stored in its internal RAM memory 38
and compares the authorized boards in this list with the received
assignment code. If the board recited in the lockbox assignment code is
one of those stored in agent key memory 38, the key transmits the third
signal (c) to lockbox 12. This third signal (c) is received and decoded by
optoelectronic communications port 24 and CPU 30 of lockbox 12. An output
from CPU 48 to a lockbox compartment lock 55 then causes the compartment
to open.
Lockbox CPU 48 maintains a lockbox access log in a lockbox RAM memory 54
which logs all accesses. Each entry in the log includes the key's
identifier code, the time and date of the attempted access (obtained from
an internal calendar-clock circuit 52), and the access result. The access
result entry can, for example, indicate: access allowed, key on lockout
list, daily timed disable lockout, or unarmed key (lockout list and daily
timed disable are discussed below). The lockbox RAM memory can log such
information on 100 lockbox accesses.
This log can later be retrieved by the reader key 16. Such operation
transfers a copy of the access log to the reader key for later display by
the data communicator unit 20.
The reader key 16, shown in FIG. 4, is similar in many respects to agent
key 14. It includes a CPU 56, an optoelectric communications port 58, a
battery 60, a "READ" button 62 and a large RAM memory 64. The access log
stored in lockbox RAM 64 can be transferred to the reader key RAM 64
simply by pressing the "READ" button and optically coupling the reader key
and the lockbox. If optical coupling is not achieved within a preset time
period, the key returns to its inactive state. The reader key RAM 64 is
large enough to store the access logs of ten different lockboxes.
Like the agent key 14, the reader key 16 is initially activated by a
programming routine that is run on data communicator unit 20. This routine
loads a variety of information into the reader key, such as the identity
of the operating agency and the length of the preset delay period.
Thereafter, no further programming is required. (Memory pointers to reader
key RAM 64 are reset each time the contents of the RAM are transferred to
the data communicator unit.)
The data communicator unit 20 includes a single board computer (SBC) 66
having an optoelectronics port 68 identical to that included in lockbox
12. This port is constructed as part of a nest 70 designed to receive any
of the three keys (agent key 14, reader key 16 and programmer key 18).
When a key is inserted in the nest, it becomes optoelectronically coupled
to the single board computer 66 inside the data communicator unit. The
single board computer can retrieve access log data from the keys or load
new operating parameters into them (discussed below). In this manner, keys
can be loaded with, and dumped of data as appropriate.
Data communicator unit 20 is typically installed, in the Level One system,
at the real estate board office and is connected to a CRT monitor 72, a
printer 74 and a keyboard 76. When a reader key 16 is inserted into the
data communicator unit nest 70, the access log data stored in the key can
be retrieved and displayed on monitor 72 or printed by printer 74. In this
manner, a record showing which agents visited the homes and at what times
can be provided.
Data communicator unit 20 can also be used, in conjunction with the
programmer key 18, to reprogram lockboxes 12. Programmer key 18, shown in
FIG. 5, is again similar to agent key 14. It includes a CPU 78, an
optoelectronic communications port 80, a battery 82, a small keypad 84 and
a RAM memory 86. The programmer key RAM memory 86 is loaded by the data
communicator unit 20 with information destined for the lockbox 12. The
information loaded into programmer key 18 includes the listing agent and
the listing agency, and serves to enable various lockbox features, such as
daily timed disable and lockout list (these features are discussed below).
When programmer key 18 and lockbox 12 are subsequently optically coupled,
this information can be transferred from the programmer key RAM 86 to the
lockbox RAM 54 by pressing a "PROGRAM" button on programmer key keypad 84.
In more detail, reprogramming of the lockbox is effected as follows. The
programmer key 18 is first inserted into the data communicator unit nest
70. A lockbox programming routine, stored in a data communicator memory
88, is then run on the data communicator single board computer 66. This
routine allows various parameters and features of the lockbox (as
discussed above) to be changed. The reprogramming routine presents menus
on the CRT monitor 72 to facilitate such programming. When suitable
lockbox program parameters have been established, the data communicator
unit single board computer 66 loads them into the memory 86 of the
programmer key 18. The programmer key can then be taken from the data
communicator unit nest 70 to the lockbox and can transfer the new
operating parameters to it through the two units' optoelectronic
communications ports. All "programming" of lockbox 12 referenced below is
effected, in the Level One system, by this technique.
The following discussion details some of the functions of the preferred
embodiment of the Level One system:
Daily Lockbox Disable
Oftentimes, homes listed by real estate agents are not vacant. The current
owners are still residing in the house and may not welcome visitors at
certain hours. For example, a homeowner may wish that his house not be
shown between the hours of 7 p.m. and 10 a.m. Accordingly, CPU 48 of
lockbox 12 can run a software routine, stored in lockbox memory 54, that
disables the lockbox from opening during certain predetermined hours of
the day. The daily lockbox disable software routine operates in
conjunction with the real time clock 52 internal to the lockbox. This
function is enabled by selecting the Daily Timed Disable option which
appears on the CRT 72 during programming of the programmer key 18 by data
communicator unit 20. If this option is selected, the data communicator
unit 20 then asks the times during which the lockbox is to be disabled.
This data is loaded into the programmer key 18, which in turn loads it
into the lockbox memory 54, as discussed above.
Key Expiration
To enhance security of the system, some or all of the agent keys 14 can be
programmed to expire (become disabled) after a certain number of days or
weeks. By this technique, keys that are lost or stolen lose their utility
in a relatively short time. The key expiration feature can be implemented
using a real time clock 90 internal to agent key 14, or can be based
simply on a long term timer (not shown). If this feature is adopted, the
supervising authority (typically the real estate board) can then specify
how long the key is to remain active before automatically disabling
itself.
After a key has expired, it must be rejuvenated (in the Level One system)
by a data communicator unit 20 before it can be used again.
Lockbox Disable
At times, it may be advantageous to render the contents of the lockbox 12
inaccessible to everyone at all times. This is another lockbox operation
option that can be selected when lockbox functions are loaded into the
programmer key 18 by a data communicator unit 20.
Key Disable
The agent key 14 can be deactivated, upon command, to disable its further
use. For example, when an agent leaves his employment, he may wish to
disable his key so that no one can take it from storage and use it. After
being deactivated by the agent, the key must be reinitialized by a data
communicator 20 before it can be used again.
Electronic Shackle Release
The shackle 22 or mounting bracket which secures the lockbox to the
structure is, in the preferred embodiment, electronically releaseable.
Certain agent keys 14 can exercise this capability by pressing a "SHACKLE"
button on the agent key keypad 30. However, not all agent keys are able to
release all lockbox shackles. In order for an agent key to release a
shackle, the key must have certain authorization bits set in its RAM
memory 38. Depending on which bits are set, the key will be able to
release shackles of lockboxes assigned to that agent, to that agent's
agency, or to that agent's board. (The agent key determines the lockbox
assignment from the contents of the second signal (b), which identifies
the parties that are authorized to unlock the lockbox.) By allowing real
estate agents, rather than just real estate board employees to remove
lockboxes, administration of the system is greatly facilitated.
Lockbox Disable Upon Removal
After a real estate agent has released a lockbox shackle, the lockbox could
normally be reinstalled on another house. Before such installation,
however, the lockbox must be reprogrammed with a variety of information,
such as the listing agent, the listing agency, the listing number, the
daily timed disable periods, etcetera. This reprogramming is normally
accomplished by loading a programmer key 18 with the new data and loading
the lockbox from the programmer key, as discussed above.
In large systems (discussed below), the above "on the fly" reprogramming
procedure is undesirable. It does not guarantee that the data loaded into
the programmer key 18 is actually transferred into the lockbox. In systems
where data integrity is important, it is desirable that the lockbox be
programmed directly by the system (by a "pod," as discussed in the Level
Two system, below) without the use of an intermediate programmer key. To
insure that "on the fly" reprogramming of lockboxes is not done, a Lockbox
Disable Upon Removal feature is selectably provided.
When the Lockbox Disable Upon Removal feature is used, the lockbox becomes
disabled when the shackle is released. In this disabled state it cannot be
reprogrammed by the programmer key; it must be returned to the board (or
agency) office for reprogramming. By requiring the lockbox be returned for
reprogramming, the board is more reliably informed of the program status
of each lockbox, and the integrity of the board's lockbox database is
maintained.
Data Communicator Unit Protection
The software resident in the data communicator unit 20 contains sensitive
information and coding which, if widely known, could pose a threat to the
security of the listed houses. Accordingly, it is important that this
software not be available to unauthorized users.
Normally, once a software pirate has gained access to a ROM chip containing
CPU software, it is a simple matter to copy the chip and dump its contents
in a computer listing. The code can then be disassembled and examined to
discover the proprietary information.
To avoid this potential problem, the software in the data communicator unit
of the present invention is stored in a volatile RAM memory 88. As long as
power is provided constantly to this memory, its contents will remain
intact. If, however, power is momentarily lost, all software stored in the
RAM will be lost as well. Interrupt switches 92 are provided inside the
data communicator enclosure to interrupt power to this RAM if the
enclosure is opened. In this manner, security of the software stored in
the RAM is provided. (The data communicator is normally powered by
conventional alternating current, but has a built-in battery back up to
protect against loss of software in the event power fails.)
If someone tampers with the data communicator unit, causing the RAM 88 to
lose all software, the data communicator must be reprogrammed by the
vendor. This can be done either by sending the unit back to the vendor or
by reprogramming over telephone lines, as discussed more fully below. In
either event, the vendor would reprogram the unit only after the issue of
the data communicator's physical security had been investigated and
resolved.
Communicator Security While In Shipment
As noted, the data communicator unit 20 contains sensitive information that
might be used to breach system security if used by unauthorized persons.
The RAM based software, described above, is one technique for preventing
improper use of the data communicator software. Another concern, however,
is that a data communicator unit might be intercepted from the mail while
being shipped from the vendor to the end user. Even without opening the
enclosure to pirate the RAM software, the mere possession of the unit by
unauthorized persons poses some security risk.
To overcome this problem, the data communicator units are shipped in a
disabled mode. For example, they can be shipped with software that will
not operate until it receives certain enabling code sequences. The vendor
could call the recipient and give these codes orally after the data
communicator's safe arrival had been confirmed. The user could then enter
these enabling codes into the data communicator unit with the keyboard 76.
Alternatively, if a phone line is coupled to the data communicator unit
(as described below), the enabling codes, or the entire data communicator
software can be transmitted from the vendor directly to the data
communicator unit. In either case, the data communicator would be useless
to those who obtained mere possession of the unit.
Agent/Reader Keys
Normally, the agent who uses an agent key will not need the capability of
retrieving data from a lockbox. However, to minimize costs of
administering the system, it is sometimes desirable that agents be able to
retrieve such data and return it to the agency or board office. In such
case, the agent key can be equipped with the functions of a reader key,
together with a correspondingly large memory, to facilitate transfer of
access logs from lockboxes to the agency or board office.
Acoustically Coupled Key
Normally, the access log data retrieved from lockbox 12 by reader key 16 is
transferred to the system (i.e. the data communicator unit 20)
optoelectronically. In certain instances, described more fully below, it
may be desirable to download data from the reader key over telephone
lines. For this function, reader key 16 is equipped with an audible tone
generator 94 which can be selectively enabled by the user. When so
enabled, it can transmit data in an acoustical, rather than an optical
format. The key can be held up to the mouthpiece of a telephone to effect
the acoustical coupling to the phone line. By this technique, data can be
downloaded from a reader key to a data communicator unit coupled to a
phone line (discussed below) without the necessity of physically returning
the key to the data communicator unit.
Mark File
As noted, the access log maintained in the memory 54 of the lockbox 12
contains data relating to the last 100 accesses. Transfer of this data to
a reader key or to an agent/reader key is accomplished quickly, due to the
use of optical communications. If, however, the reader key uses its
acoustical coupling capability to transfer this data to the system, the
resulting data transfer takes a comparatively long time, during which the
reader key and telephone handset must be maintained in acoustical
communication. Maintaining acoustical communication between these units is
not difficult, but can be made even more simple if the data transmission
is shortened. Oftentimes, not all 100 past accesses are of interest. For
example, the supervising real estate board or agency may only be
interested in accesses over a certain period of time. To facilitate this
function, the lockbox memory 54 can be marked with one or more flags. This
memory can then be read from the last flag to the end, or just between two
flagged positions. By this technique, only the data of interest is
transferred.
As noted, the mark file function is useful when a real estate agency or
board is interested in monitoring the access to a home during a specific
period, as for example during a weekend that the house is advertised in
the newspaper. In such case the lockbox can be commanded, with a
programmer key, to flag the next memory location as the beginning of the
flagged list. This would be done on Friday evening. An agent would then
return Monday morning and recover just the entries in the access log made
since the flagged time. Alternatively, the agent could insert a second
flag in lockbox memory 54 without retrieving the data, thereby allowing
the flagged entries from this time period to be recovered later. If a
lockbox is moved from one house to another, a flag can mark the move so
that the move is indicated on the access log. Data can then be selectively
recovered from the lockbox so that only accesses at the new location are
recovered.
As another option, the reader key or agent/reader key can be operated to
retrieve only the last N entries stored in the lockbox access log (where N
is selected by the user). This may be useful, for example, to determine
who recently opened the lockbox.
Reed Switch
The photodetector 28 in the optoelectronic port 24 of the lockbox 12
generates a signal whenever it is exposed to light. Such a signal can be
used to switch a lockbox from an idle to an active state. Such
photodetectors, however, are also sensitive to ambient light, such as
sunlight and porch lights. To prevent the undesired activation of the
lockbox, and consequent increased drain on its internal battery 50, a reed
switch 96 is provided in the power circuitry of the lockbox. This reed
switch is normally open, thereby leaving all of the lockbox circuitry,
except the internal clock 52 and memory refresh circuitry, in an unpowered
state. A magnet 98 is mounted in the optoelectronic communication port of
each key and causes the lockbox reed switch 96 to close when the key is
brought in close proximity thereto. In this manner, the lockbox is
maintained in a substantially idle state until a key is held in proper
position. Power is then applied to all lockbox circuits and the lockbox
becomes active. This reed switch feature also increases security by
rendering the lockbox unresponsive to attempted accesses by makeshift
keys.
Preload Permission Code
As noted, the agent key 14 must be held next to the lockbox 12 in order for
the units to communicate optoelectronically. Although not usually a
problem, this task is sometimes difficult when the lockbox is mounted in
an awkward location, such as on a water spigot mounted at ground level.
Ordinarily, the agent would have to engage the key with the lockbox in
such position and then start pressing buttons on the agent key
corresponding to the required password and auxiliary permission codes
(discussed below). This task is even more tedious at night.
To obviate this potential problem, the agent key 14 of the present
invention can be preloaded with all of the password and permission codes
needed to access the lockbox. The key can then be mated momentarily with
the lockbox and the handshaking exchanges made automatically upon closure
of the lockbox reed switch 96. Thus, the agent need not press a single key
in the dark or cramped location in which the key and lockbox are mated in
order to open the lockbox. The password and auxiliary permission codes can
be preloaded in a well-lit, convenient location, such as in a car. The
agent then has two minutes within which to use the preloaded agent key to
open the lockbox. After this period the preloaded information is lost,
thereby aiding in system security. This feature greatly facilitates
opening lockboxes mounted in awkward or poorly lit locations.
Audit Trail
Occasionally, a vendor will receive reports that a lockbox or key is
inoperative. To aid in investigations of such reports, the lockbox and
keys of the present invention include a section of their RAM memories
dedicated to storing detailed information on the last ten attempted
operations. This information identifies the type of operation attempted,
whether it was successful, and any error messages generated by an
unsuccessful operation.
The audit trail of an exemplary agent key operation might be as follows.
The key is energized by the "ON" button. The four digit password is then
entered, followed by a keystroke (or keystrokes) identifying the desired
operation (such as release shackle or open lockbox). If an incorrect
password is entered, an unsuccessful attempt to arm the key would be
stored in the agent key audit trail, with an error message indicating use
of an incorrect password. If an operation is attempted but is unauthorized
(i.e. unauthorized shackle release), a corresponding entry would be made
in the agent key audit trail.
The audit trail of an exemplary lockbox operation might be as follows. The
lockbox is activated by closure of the reed switch, but the key is
improperly inserted so that optical communication cannot be established.
An unsuccessful attempt to communicate with the lockbox would then be
logged in both the lockbox and agent key audit trail.
Upon reports of a malfunctioning lockbox or key, the corresponding audit
trail can be retrieved, either by sending the unit to the vendor or by
coupling it to the vendor through a modem (described herein) to facilitate
resolution of the anamoly.
Lock Out List
In certain instances, it may be desirable to lock out certain agents, or
agents from certain agencies, and thereby deny them access to a listed
property. In the preferred embodiment, RAM 54 of lockbox 12 contains a
list of key identifier codes that, although nominally valid, are to be
locked out. The identifier code of the accessing agent key is compared
against this list by lockbox CPU 48. If the accessing key's identifier
code is found in this list, lockbox 12 will abort the handshaking exchange
and deny access to the key compartment.
As a further option, the lockbox CPU 48 can be programmed to disable any
locked-out keys that attempt to access the lockbox. In this case, lockbox
CPU responds to the first signal sent by the agent key with a special
second signal that scrambles the RAM memory 38 of the agent key so that
the key is rendered inoperative. In the preferred embodiment, the lockbox
scrambles the four digit password that must be entered by the user to
"arm" the agent key, by replacing certain digits of the password with
hexadecimal digits (A-F) which are not included on the agent key keypad
30. With the password thus scrambled, the user can no longer "arm" the key
and initiate a handshaking exchange with any lockbox. The password can
only be unscrambled by reprogramming the agent key, which operation is
usually only performed by the supervising real estate board.
Exclusive Listings
At times, an agency may wish to list a property exclusively, denying access
to agents from other agencies. In this case, the lockbox is programmed to
open only for agents from the listing agency, and to deny access to all
others.
Multi-Board Capability
It is sometimes desirable to make a listed house available to agents from a
plurality of different real estate boards. Normally, keys owned by one
real estate board will not be able to open lockboxes owned by another real
estate board (the second signal (b) sent from the lockbox to the key will
not correspond to a lockbox that the key is authorized to unlock). In the
present invention, a section of lockbox memory 54 is used to store
identification codes identifying up to fifteen real estate boards which
are authorized to access the lockbox. All fifteen of these board
identification codes are sen | | |
