Telephonic communications – Plural exchange network or interconnection – Multi-pbx interconnection
Reexamination Certificate
2000-07-17
2004-03-02
Bui, Bing (Department: 2642)
Telephonic communications
Plural exchange network or interconnection
Multi-pbx interconnection
C379S395010
Reexamination Certificate
active
06700970
ABSTRACT:
This invention relates to a local area network (LAN) telephone system modified to provide emergency telephone service in the case of power failure or LAN processor failure.
BACKGROUND OF THE INVENTION
In a typical analog telephone system used in homes and small businesses, extension phones are connected in parallel across the telephone line conductors. In such a typical system, as shown in
FIG. 1
, a telephone line
110
comprising a wire pair extends from a public switched telephone network (PSTN) to several conventional analog telephones
121
,
122
and
123
within the premises
102
of a home or business. The telephones
121
-
123
are connected in parallel across the wire pair of the telephone line
110
. Power for the analog telephones is supplied by the telephone company on the telephone line from an uninterruptable power source (UPS) and the analog telephones require no other power source. Each of the telephones
121
-
123
can be used to make a telephone call or receive a telephone call. The system is very reliable and can and does provide uninterrupted telephone service in all but the worst national disasters. The telephone system will remain fully operative in most instances when electric power to the business or home is interrupted. However, the analog telephones
121
-
123
cannot be used to make calls to each other, cannot be used as an intercom system, and cannot transfer calls or hold calls or perform other functions provided by most modern telephone systems.
To increase the functionality of their telephone system, many small businesses and some private homes employ a private branch exchange (PBX) in a system, such as that shown in FIG.
2
. In the system of
FIG. 2
, one or more telephone lines
101
are terminated in a PBX server
210
. The PBX server
210
is separately connected by connections
221
,
222
and
223
to telephones
231
,
232
and
233
, respectively. The connections
221
,
222
and
223
can be analog or digital, but the connections are point to point, each allowing communication only between the PBX and the corresponding telephone. The configuration of
FIG. 2
allows for rich functionality because the PBX server
210
can route incoming calls to any one of the telephones
231
-
233
as well as let the telephones
231
-
233
make calls to each other, provide a hold function, provide a forwarding function, provide voice mail and many other modem telephone functions. This configuration, however, has a disadvantage in that the PBX server
210
must be powered from an external power source and if power fails or if the PBX server
210
fails, the phone service for all of the phones is interrupted.
Another typical PBX system is shown in FIG.
3
. In this system, one or more telephone lines
101
is terminated in a PBX server connected to telephones
321
,
322
and
323
over a local area network (LAN)
320
, which may be a coax cable which is connected in parallel to the telephones
321
,
322
and
323
. Alternatively, instead of the coax cable, the LAN network may be twisted pairs, such as an Ethernet 10-base T system. In any case, the telephones
321
,
322
and
323
are logically connected in parallel and can receive all data and transmit to all other end points on the LAN including transmissions via logically transparent repeaters, hubs, switches and routers. Like the PBX arrangement of
FIG. 2
, the LAN system in
FIG. 3
allows a high degree of functionality and, in addition, provides the capability of having computers connected as end points and permits computers to be used as telephones, telecopiers and answering devices. However, like the PBX server in
FIG. 2
, the PBX server
310
of the system in
FIG. 3
must also receive power from an external source and it is therefore suffers from the same weakness in that service to all of the telephones and other end points can be cut off in the event of power failure or failure of the PBX server.
The above described disadvantages of the systems of
FIGS. 2 and 3
are not major problems in large businesses because there, power can be made redundant with UPS devices and, typically, a professional maintenance staff is available. In such large businesses, PBX functions are seen as being indispensable and the businesses willingly trade the lower reliability of the PBX systems for the enhanced telephone systems that they receive from the PBX systems. However, typically, in small businesses and in private homes, there is no maintenance staff and an UPS is an unwanted expense. Accordingly, there is a need for small businesses and private homes for a telephone system which has the features of a PBX system but yet has the reliability of the old fashioned analog telephone system shown in FIG.
1
.
SUMMARY OF THE INVENTION
The system of the present invention is implemented in a LAN telephone system in which a PBX is used to route telephone calls to or from telephones or other telephonic devices of the system. In accordance with the invention, fallback adapters are provided to automatically respond to a power failure and also automatically respond to a failure of the PBX. When a power failure occurs or a PBX failure occurs, the fallback adapters directly connect the telephones to a telephone line or telephone lines of the system to enable the telephones to be used as analog phones and make and receive calls directly without using the PBX. Power failure is detected in the fallback adapters by a relay which defaults to a position to connect the telephones directly to the telephone line. In addition, the fallback detectors are provided with controller logic which detect the presence of a ringing signal on the telephone line and the failure of the PBX to respond to the ringing signal. In addition, the fallback detectors detect the failure of the PBX to respond when a telephone is used to attempt to make an outgoing call or a call to another one of the telephones. When detecting a failure of the PBX, the control logic in a fallback detector will actuate the relay in the fallback detector to its fallback positions so as to connect the corresponding telephone directly to the telephone line and allow the telephone to make and receive telephone calls as an analog telephone. In this manner, when a power failure occurs or when the PBX fails in the LAN system, the system is switched to operate in the analog mode and telephone service is maintained even though a power failure or PBX failure has occurred.
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US 201/0053125, Staples et al, Dec. 20, 2001 (Appl. 09/827,022 filed on Apr. 04, 2001), pp. 1-5.
Aronson Michael
Schmidt Thomas Joseph
Albrecht Ralph P.
AOX Incorporated
Bui Bing
Venable LLP
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