U.S. patent number RE32,263 [Application Number 06/714,457] was granted by the patent office on 1986-10-07 for charge time start control for interconnect pabx.
This patent grant is currently assigned to RCA Corporation. Invention is credited to Murray F. Kaminsky.
United States Patent |
RE32,263 |
Kaminsky |
October 7, 1986 |
**Please see images for:
( Certificate of Correction ) ** |
Charge time start control for interconnect PABX
Abstract
In an interconnect .[.PABX.]., .Iadd.telephone equipment
.Iaddend.which does not have an answer signal returned thereto,
decision logic makes use of returned audible busy and ring-back
signals to determine if a connection extended through a telephone
utility network to a called station is completed.
Inventors: |
Kaminsky; Murray F.
(Philadelphia, PA) |
Assignee: |
RCA Corporation (Princeton,
NJ)
|
Family
ID: |
27043144 |
Appl.
No.: |
06/714,457 |
Filed: |
March 21, 1985 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
470573 |
Feb 28, 1983 |
04472600 |
Sep 18, 1984 |
|
|
Current U.S.
Class: |
379/126; 379/235;
379/257 |
Current CPC
Class: |
H04M
15/34 (20130101) |
Current International
Class: |
H04M
15/34 (20060101); H04M 015/18 () |
Field of
Search: |
;179/7.1R,7R,7MM,2TC,8A,9,18AB,18AD |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schreyer; Stafford D.
Attorney, Agent or Firm: Tripoli; Joseph S. Haas; George E.
Seligsohn; George J.
Claims
What is claimed is:
1. In an interconnect PABX which includes means capable of (A)
extending a telephone connection from respective calling telephone
stations of said interconnect PABX through a telephone utility
network to respective called telephone stations, (B) receiving a
returned audible busy signal in response to either said network or
a called station being busy, and (C) receiving a returned audible
ring-back signal when a called station is ringing; an answer signal
returned by a called station to said network in response to that
called station going off-hook being unavailable to said
interconnect PABX, said answer signal being indicative of the
extended telephone connection to that called station being
completed; improved apparatus forming part of said interconnect
PABX for deciding whether or not an extended connection through
said telephone network to a called station has been completed, said
apparatus comprising:
a busy signal detector for deriving a first output in response to a
return of said audible busy signal;
a ring-back signal detector for deriving a second output in
response to a return of said audible ring-back signal;
switch means for deriving a third output indicative of whether a
calling station of said interconnect PABX is in an off-hook
condition or is in an on-hook condition; and
connection complete or incomplete decision logic means having said
first, second and third outputs applied as respective inputs
thereto for (1) deriving a first signal indicative of an incomplete
extended connection in response to either (a) the indication by
said first output of the existence of an audible busy signal or (b)
the indication by said second and third outputs of the occurrence
of a calling-station on-hook condition that occurs at the end of a
calling-station off-hook condition interval during which an audible
ring-back signal occurs and thereafter, continues to occur until
said end of said interval, and for (2) deriving a second control
signal indicative of a complete extended connection in response to
an audible ring-back signal that occurs during said interval, but
which terminates prior to said end of said interval, so that the
calling station remains in an off-hook condition for a period of
time after the audible ring-back signal has terminated.
2. In said interconnect PABX defined in claim 1, which further
includes a station message detail record means for recording toll
charges of toll telephone calls extended from a calling station of
said interconnect PABX through said telephone utility network to
called stations in accordance with the area and office codes of any
particular called station and the duration of a time period of a
toll telephone call from a particular interconnect PABX calling
station and that particular called station; and
wherein said station message detail record means is coupled to said
improved apparatus and is responsive to the occurrence of said
second control signal for starting said time period and is
responsive to said particular calling station going into an on-hook
condition at the end of said interval for ending said time period.
.Iadd.
3. In interconnect telephone equipment which includes means capable
of (A) extending a telephone connection from a calling telephone
station of said interconnect telephone equipment through a
telephone utility network to respective called telephone stations,
(B) receiving a returned audible busy signal in response to either
said network or a called station being busy, and (C) receiving a
returned audible ring-back signal when a called station is ringing;
an answer signal returned by a called station to said network in
response to that called station going off-hook being unavailable to
said interconnect telephone equipment, said answer signal being
indicative of the extended telephone connection to that called
station being completed; improved apparatus forming part of said
interconnect telephone equipment for deciding whether or not an
extended connection through said telephone network to a called
station has been completed, said apparatus comprising:
a busy signal detector for deriving a first output in response to a
return of said audible busy signal;
a ring-back signal detector for deriving a second output in
response to a return of said audible ringback signal;
switch means for deriving a third output indicative of whether a
calling station of said interconnect telephone equipment is in an
off-hook condition or is in an on-hook condition; and
connection complete or incomplete decision logic means having said
first, second and third outputs applied as respective inputs
thereto for (1) deriving a first signal indicative of an incomplete
extended connection in response to either (a) the indication by
said first output of the existence of an audible busy signal or (b)
the indication by said second and third outputs of the occurrence
of a calling-station on-hook condition that occurs at the end of a
calling-station off-hook condition interval during which an audible
ring-back signal occurs and thereafter, continues to occur until
said end of said interval, and for (2) deriving a second control
signal indicative of a complete extended connection in response to
an audible ring-back signal that occurs during said interval, but
which terminates prior to said end of said interval, so that the
calling station remains in an off-hook condition for a period of
time after the audible ring-back signal has terminated. .Iaddend.
Description
This invention relates to interconnect private automatic branch
exchanges (PABX) and, more particularly, to an improved technique
for determining whether or not connections extended from calling
stations of an interconnect PABX through a telephone utility
network to called stations have been completed.
For many years in the past, substantially all telephone facilities
(including a PABX) situated on the premises of a subscriber of a
telephone utility were provided by and were under the control of
the telephone utility. In this case, charges for metered local
calls and/or long-distance for toll calls made from any calling
station of a telephone subscriber is determined by the telephone
utility using solely telephone utility equipment.
In some cases, it is desirable to individually bill a user who uses
a calling station of a PABX who makes a call through the telephone
utility network to a called station, rather than to merely to be
able to bill the PABX subscriber. One obvious example of such a
case is that of a hotel or motel PABX, in which it is essential
that the individual hotel or motel guest be billed. Another example
is a business organization with different profit/loss centers.
Telephone utilities have developed, for their own use, telephone
systems capable of metering local calls and/or charging for
long-distance toll calls made from calling stations of such a PABX.
By way of examples, such PABX billing telephone systems are
disclosed in U.S. Pat. No. 3,721,769, which issued on Mar. 20, 1973
to Krock et al. (which is assigned to GTE Automatic Electric
Laboratories Inc.) and in U.S. Pat. No. 4,090,034, which issued May
16, 1978 to Moylin (which is assigned to Bell Telephone
Laboratories).
As known in the telephone art, there are several well known audible
signals which are returned to the calling-station user. These
audible signals include, among others, dial tone, all-trunks busy,
called-station busy and ring-back. Each of these audible signals is
distinctive and its call-status meaning is well known and easily
recognized by calling-station telephone users. However, not all
types of call-status signals are returned to the user of a calling
telephone station. For instance, when a telephone connection is
extended from a calling station through a telephone utility network
to a called station, the called station, on going off-hook, returns
an answer signal (commonly known as answer supervision) to the
telephone utility network. This answer signal, which is a
call-station signal indicative of a completed extended connection
to the called station, is available to the telephone utility for
determining the start of the time-charge period for either a
metered local call or a long-distance toll call made from a calling
station of a calling subscriber. However, this answer signal, which
is returned from a called station to the telephone utility network,
is not commonly further returned or made available by the telephone
utility network to any of the equipment (including a PABX) situated
at the calling subscriber's premises.
As long as the telephone utility network is the provider of a
telephone subscriber's PABX, it is not essential that the answer
signal returned to the telephone utility network be further
returned to the PABX (although it might be less costly if the
answer signal were available at the PABX). However, recently
telephone subscribers have been installing on their premises
so-called interconnect telephone equipment which is not furnished
by the telephone utility. In the case of an interconnect PABX, no
answer signal is returned to the interconnect PABX in response to
the completion of the extension of a connection from a calling
station of the PABX through the telephone utility network to a
called station. How, then, can the possessor of an interconnect
PABX (e.g., hotel or motel operator, a business owner, etc.)
determine the proper charge time period for a metered local call or
a long-distance toll call made by a user (hotel or motel guest,
business employee, etc.) of a calling station of the interconnect
PABX through the telephone network to a called station?
Currently, the answer to this question is to make a tentative
assumption that the extension of a connection, from an interconnect
PABX calling station through the telephone utility network to a
called station, is completed, so that in all cases a charging time
period is started. If the charging time period starts a given few
seconds following the dialing of the last digit by the calling
station and lasts a predetermined short interval (e.g., 20 seconds)
without the calling station going on-hook, the tentative assumption
is made permanent and a charge for the metered or long-distance
toll call is made to the user of the calling station of the
interconnect PABX. However, if the calling station goes on-hook
within the short interval (e.g., 20 seconds), the tentative
assumption that the extended connection has been completed is
reversed and the charge time period therefor is cancelled.
While statistically this current solution is reasonably accurate,
it is plain that there are occasions when (A) charges are made for
telephone calls in which the extension of connection to the called
station has never been completed (e.g., whenever a calling station
user stays off-hook for more than 20 seconds despite the fact that
a busy signal or a ring-back signal is returned continually during
the entire interval in which the calling station user is in an
off-hook condition), and (B) no charge is made to a calling station
user of the interconnect PABX when the total time for the
completion of the completed extended connection plus the
conversation time period is less than the predetermined interval
(e.g., less than 20 seconds). This is particularly a problem where
short data calls may be made, information exchange performed and
the call terminated (e.g. credit verification).
The present invention is directed to an improved technique
available at the interconnect PABX for more accurately determining
whether or not a connection extended from a calling station of the
interconnect PABX through a telephone utility network to a called
station has been completed, despite the fact that no answer signal
is returned from the called station to the interconnect PABX in
response to the completion of the extension of a connection
thereto. More specifically, in accordance with principles of the
present invention, improved apparatus forming part of the
interconnect PABX decides whether or not an extended connection
through the telephone utility network to the called station has
been completed. The improved apparatus comprises a busy signal
detector for deriving a first output in response to a return of an
audible busy signal; a ring-back signal detector for deriving a
second output in response to a return of an audible ring-back
signal; switch means for deriving a third output indicative of
whether a calling station of the interconnect PABX is in an
off-hook condition or is in an on-hook condition; and connection
complete or incomplete decision logic means having the first,
second and third outputs applied as respective inputs thereto for
(1) deriving a first control signal indicative of an incomplete
extended connection in response to either (a) the indication by
said first output of the existence of an audible busy signal or (b)
the indication by the second and third outputs of the occurrence of
a calling station on-hook condition that occurs at the end of a
calling station off-hook condition interval during which an audible
ring-back signal occurs and thereafter continues to occur until the
end of the interval, and for (2) deriving a second control signal
indicative of a complete extended connection in response to an
audible ring-back signal that occurs during the interval, but which
terminates prior to the end of the interval, so that the calling
station remains in an off-hook condition for a period of time after
the audible ring-back signal has terminated.
In the drawings:
FIG. 1 is a block diagram illustrating the relationship among an
interconnect (non-telephone utility) PABX, a telephone utility
network and a called station that is not part of the aforesaid
interconnect PABX (but which may or may not be part of another
interconnect or non-interconnect PABX);
FIG. 2 is a functional block diagram of one typical embodiment of
an interconnect PABX, and
FIG. 3 illustrates a block diagram of charge-timing-period
start-control apparatus incorporating the principles of the present
invention.
Referring to FIG. 1, there is shown in block diagram interconnect
(non-telephone utility) PABX 100, telephone utility network 102 and
called station 104 to which a connection may be extended from a
calling station of PABX 100 through telephone utility network 102.
More specifically, interconnect PABX 100, in response to the
dialing of a predetermined access digit by a calling station
thereof, extends a connection over a telephone line 106 from that
calling station of PABX 100 to telephone utility network 102. As is
usual, telephone utility network 102 returns a dial tone over
telephone line 106 to the calling station of PABX. The calling
station which may be either a rotary dial telephone or a
push-button dial telephone) forwards connection-extending dialed
digit signals over telephone line 106 to telephone utility network
102. Telephone utility network 102, in response to these dialed
digit signals, extends a connection over telephone line 108 to a
called station 104 (which called station may be anywhere in the
world and may or may not be part of another PABX). Should any of
the facilities of telephone utility network 102 be busy or should
called station 104 itself be busy, telephone utility network 102
returns an audible all-trunks busy signal or an audible
called-station busy signal over telephone line 106 to PABX 100.
Assuming that neither telephone utility network 102 or called
station 104 is busy, telephone utility network 102 forwards a ring
signal to called station 104 over telephone line 108, while, at the
same time, returning an audible ring-back signal over telephone
line 106 to PABX 100. Should called station 104 be answered (i.e.,
go off-hook), an answer signal is returned to telephone utility
network 102 over telephone line 108. However, telephone utility
network 102 does not further return an answer signal over telephone
line 106 to PABX 100. Thus, in summary, the only control signals
returned by telephone utility network 102 to PABX 100, in response
to making a call to called station 104 are those that can be
returned over an audible connecting path, such as dial tone, an
audible busy signal and an audible ring-back signal.
FIG. 2 is a functional block diagram of one typical embodiment of
interconnect PABX 100. PABX 100 includes a plurality of telephone
stations 200-1 . . . 200-N (where N is a plural integer). Each of
telephone stations 200-1 . . . 200-N can comprise a standard dial
telephone, or, alternatively, some other type of terminal
equipment, such as a teletype, a data phone, an on-line computer,
etc. In any event, telephone stations 200-1 . . . 200-N are
associated with switching means 202. Also associated with switching
means 202 is signal detectors and controller 204. Signal detectors
and controller 204 has access to station message detail recording
means 206. As usual in a PABX, any one calling one of telephone
stations 200-1 . . . 200-N can extend a connection through
switching means 202 to any called one of telephone stations 200-1 .
. . 200-N by dialing the extension number of the called station of
PABX 100. In response to this dialing, switching means 202 is
operated by the controller of block 204 to extend the connection to
the called telephone station 200-1 . . . 200-N of PABX 100. Should
any one calling one of telephone stations 200-1 . . . 200-N desire
to extend a call connection through telephone utility network 102,
a predetermined access digit is dialed, which causes switching
means 202 to be operated by the controller 204 to extend a
connection to telephone utility network 102 from that calling one
of telephone stations 200-1 . . . 200-N through telephone line 106.
Block 204 includes signal detectors for selectively detecting
various audible signals forwarded thereto through switching means
202 from telephone stations 200-1 . . . 200-N and also from
telephone utility newtwork 102 over telephone line 106. These
audible signal detectors may include audible dialed digit signals
(in the case of PABX push-button dial telephones), but always
include audible busy signal and ring-back signal detectors. Also
included in block 204 are signal detectors for detecting the
on-hook/off-hook condition of each of telephone stations 200-1 . .
. 200-N.
Block 204 in combination with block 206, includes means for
determining and recording information required to charge an
individual user of PABX 100 for metered local calls and/or
long-distance toll calls extended through telephone utility network
102. In some cases (such as in the case of a hotel or motel PABX)
each of telephone stations 200-1 . . . 200-N is assumed to be a
user. In other cases (such as in the case of a business PABX) the
user (such as an employee) may have a personal identification
number which is dialed by him whenever he makes a charge call from
any one of calling stations 200-1 . . . 200-N. In any event,
information required to charge for a call includes the charge time
period of the call (i.e., the portion of the calling-station
off-hook interval that extends from the start of charging for a
call until the calling-station goes on-hook) and, in the case of a
long-distance toll call, the area and office codes of the called
station. Block 204 and/or block 206 contain conventional
toll-ticketing equipment for measuring the length of the charge
time period, determining the charge rate for a toll call and
recording in station message detail recording means 206 details of
each charged telephone call. These details also can include the
time of day, the dialing number of the called station, total number
of called facilities used, etc.
PABX equipment for performing the functions so far described for
interconnect PABX 100 of FIG. 2 is well known in the art and
includes the PABX equipment disclosed in each of the aforesaid U.S.
Pat. Nos. 3,721,769 and 4,090,034. What makes interconnect PABX 100
different from the telephone-utility provided PABX equipment of the
prior art is that interconnect PABX 100 has no way of ever having
returned thereto answer signal information (as do some of the
telephone-utility provided PABX equipments of the prior art) for
determining the occurrence of the start of a charge time period. In
order to accomplish this function, signal detectors and controller
204 of interconnect PABX 100 includes the charge-timing-period
start-control apparatus shown in block diagram form in FIG. 3.
Referring to FIG. 3 there is shown ring-back signal detector 300
and busy signal detector 302, which respond, respectively, to an
audible ring-back signal and to an audible busy signal returned
from telephone utility network 102 over telephone line 106 (which
audible signals are forwarded by switching means 202 to block 204).
Ring-back signal detector 300, in response to the detection of an
audible ring-back signal, provides a first output which is applied
as a first input to call complete or incomplete decision logic 304.
Busy signal detector 302, in response to the detection of an
audible busy signal, provides a second output which is applied as
second input to call complete or incomplete decision logic 304.
On/off-hook switch 306 produces a third output indicative of the
on-hook or the off-hook condition of the particular calling station
of PABX 100 attempting to extend a connection through telephone
utility network 102 to a called-station 104. The third output from
on/off-hook switch 306 is applied as a third input to call complete
or incomplete decision logic 304. Call complete or incomplete
decision logic 304 can take the form of a hard-wired logic circuit
or, alternatively, it can take the form of a software programmed
signal processor. In any event, call complete or incomplete
decision logic is selectively responsive to the respective first,
second and third inputs thereto from ring-back signal detector 300,
busy signal detector 302 and on/off-hook switch 306 to logically
decide either a first control output 308 therefrom indicative of
"no charge" or a second control output 310 therefrom indicative of
"start-call timing." A logical relationship between the respective
"no charge" and "start call timing" outputs from call complete or
incomplete decision logic 304 and the condition of each of the
respective first, second and third inputs thereto is shown in the
following table:
TABLE I ______________________________________ Condition Output
______________________________________ 1 Busy signal detected
No-charge 2 Ring-back signal No-charge detected continually until
"on-hook" occurs 3 Ring-back signal Start call detected followed by
a timing (upon termination of ring-back ring-back signal while
"off-hook" termination) remains
______________________________________
Despite the fact that the interconnect PABX 100 never has an answer
signal returned to it from telephone utility network 102, it can be
seen from the above table that call complete or incomplete decision
logic 304 is able to make use of the audible ring-back signal or
the audible busy signal (which are returned to PABX 100 from the
telephone utility network 102) in a logical manner to determine
quite accurately (i.e., on the basis of very good circumstantial
evidence) whether or not the extended connection through telephone
utility network 102 to a called station has, in fact, been
completed. This, in turn, permits the start of timing for charging
purposes to be determined much more accurately than was heretofore
possible in the case of an interconnect PABX, which does not have
available to it the actual answer signal returned from the
called-station.
* * * * *