GTL 1019
`IPR of U.S. Pat. No. 7,529,357
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`

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`US. Patem
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`Mar. 4, 1980
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`Sheet 1 of 4
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`US. Patent Mar. 4, 1980
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`US» Patent Mar. 4, 1980
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`Sheet 3 of4
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`RECEIVE 800-NXX-XXXX
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`
`
`

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`US. Patent Mar. 4, 1980
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`Sheet 4 of4
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`1
`
`DATA BASE COMMUNICATION CALL
`PROCESSING METHOD
`
`TECHNICAL FIELD
`
`This invention relates to communication call routing
`and particularly to a method for automatically process-
`ing telephone call data from a telephone system over
`CCIS (Common Channel Interoffice Signaling) direct
`signaling facilities to a remote_data base for translation
`into a call control message which is then sent to the
`telephone system for controlling the further completion
`of call connections to a destination in accordance with
`the control message.
`The invention specifically pertains to procedures for
`processing an INward WATS (Wide Area Telephone
`Service) call over the CCIS facilities to a data base
`system for obtaining the number of an available station
`to which the call is to be completed.
`BACKGROUND ART
`
`INward WATS is popularly known as INWATS and
`is frequently referred to as the “800” number toll-free
`telephone service. It allows a customer to establish an
`area of the country from which he can receive calls
`without charge to the calling parties. In the United
`States, the service is currently available for both intra-
`state and interstate calls. Tariff costs for the service are
`based on the number of customer lines, the band of rate
`states selected, the total monthly hours of usage, and the
`total number of calls completed.
`Over the last decade, the volume of INWATS calls
`has increased to the extent that INWATS traffic has
`
`become a substantial percentage of all toll calls served
`by existing telephone switching systems. The service
`has proven to be especially useful for business custom-
`ers in obtaining travel and hotel reservations, purchase
`orders, and the like.
`the
`Despite the commercial success of INWATS,
`ever expanding customer demands for the service and
`the projected extension of INWATS for international
`calling has presented a number of problems for the
`telephone industry and its customers. Prevalent among
`the problems are: (1) the rigid geographic bands for
`INWATS, (2) the requirement for a multiplicity of
`INWATS numbers, (3) routing and numbering ineffi-
`ciencies due to service entitlement check operations of
`originating and terminating screening offices, (4) inef-
`fective attempts due to all INWATS customer lines
`busy conditions caused, for example, by mass calling to
`800 numbers advertised, for example, on television, and
`(5) the absence of traffic statistics for INWATS custom-
`ers on the number of calls made from each area code.
`To elaborate, in the United States, a customer pur-
`chases the service on intrastate and/or interstate bases
`and is supplied with one or more INWATS numbers.
`Such an arrangement is necessary because of state and
`federal tariffs. Interstate INWATS is currently offered
`for a maximum of seven geographic bands. Band 1 gen-
`erally involves all states bordering the customer home
`state; Band 2 typically includes all of Band 1 and addi-
`tional states bordering Band 1; Band 5 presently covers
`the continental United States; Band 6 adds Hawaii and
`Alaska; and Band 7 includes Puerto Rico and the Virgin
`Islands. In some cases, multiple bands of intrastate ser-
`vice are also offered. Customers purchase the various
`
`10
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`4,191,860
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`2
`service bands on a 240 hours/month or a 10 hours/-
`month basis.
`
`The rigid band assignment heretofore has required a
`customer to purchase an entire band encompassing
`many different telephone area codes even though the
`customer may desire INWATS service only in a portion
`of that band. A need has therefore existed for a proce-
`dure and equipment which fulfills customer requests for
`INWATS service covering only desired telephone area
`codes.
`
`A principal INWATS problem has been the necessity
`for the purchaser in many instances to be assigned a
`multitude of different INWATS numbers. Illustratively,
`several airline reservation services with multiple re-
`gionalized answering points presently are provided
`with between 10 and 20 different: INWATS numbers to
`obtain
`reasonably
`economical
`INWATS service
`throughout the United States. The different numbers
`are required by the customer because of geographical
`location, business hours and the designs and operations
`of existing switching equipment. Such multiple number
`requirements have proven to result in customer and user
`confusion, errors in directory number listings and ad-
`vertising, as well as complications in obtaining direc-
`tory assistance for nonlocally published INWATS num-
`bers and in conformity with the call originating area
`codes. New call processing techniques and facilities are
`therefore needed to eliminate the plural numbers for
`each INWATS customer.
`An INWATS number presently includes a special
`area code of 800, followed by a specific NNX code for
`the terminating NPA (Number P'lan Area), followed by
`a four digit number XXXX. “N” in the code refers to
`any digit except 0 or 1 and “X” refers to any one of 10
`digits. Of the NNX codes, all NN2 codes are currently
`reserved for intrastate use. At the present time, each
`NPA in the United States is assigned one NNX code
`with the exception of the NPAs 212, 312 and 213 each
`of which have two NNX codes.
`INWATS number usage is readily understood by
`considering an example of a typical INWATS call.
`Assume that a party in Indianapolis wishes to place a
`call to an INWATS customer with the assigned number
`800+24l +2312 in the Atlanta, Georgia area. After the
`caller dials the number, the call is routed to an originat-
`ing screening office which utilizes the 800+24l to de-
`termine both the terminating city (Atlanta) and the band
`of the calling party with respect to the terminating city.
`The screening office then sends a number 142+ 2312 to
`a terminating screening office for Atlanta. The under-
`lined “2” indicates that Indianapolis is in Band 2 with
`respect to Atlanta and the “4” represents the 241 NXX
`code. On the basis of the received 142+2312, the termi-
`nating screening office ascertains whether or not the
`call originated from a permissible rate band purchased
`by the called custmer. If the call is entitled to be com-
`pleted,
`the terminating screening office controls the
`establishment of call connections to the called cus-
`tomer.
`
`A disadvantage of the foregoing INWATS call pro-
`cessing arrangements is that INWATS call screening,
`routing and service entitlement checking functions are
`performed by costly, complex and special INWATS
`facilities integrated into many individual originating
`and terminating screening offices throughout the nation
`and without call rerouting capability in such offices in
`the event of call overload or equipment failure. Another
`disadvantage is that no procedure is available for deter-
`
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`

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`4,191,860
`
`3
`mining the busy condition of INWATS customer lines
`before calls are switched through the toll network.
`Present day switching systems determine that all IN-
`WATS customer lines are busy only after the calls are
`routed through the originating and terminating screen-
`ing offices to the local terminating office. As a conse-
`quence, the telephone network occasionally is over-
`loaded, particularly during heavy traffic periods by
`mass calling to the all busy INWATS customer lines.
`Such overloads obviously are undesirable and prove to
`be a problem for telephone companies especially be-
`cause no facilities are available for dynamically identify-
`ing INWATS customer busy conditions and then pre-
`cluding the toll switching of INWATS calls to that
`customer.
`
`Another disadvantage is that existing telephone sys-
`tems and call processing techniques have been unable to
`provide adequate traffic data to INWATS customers on
`the number of calls received from a given geographic
`area. The data would aid in the determination of the
`numbers of INWATS lines and stations as well as the
`personnel needed to serve the calls. It would also enable
`customers to determine whether the serivce is economi-
`cally warranted for that area.
`DISCLOSURE OF THE INVENTION
`
`The foregoing problems are solved and a technical
`advance is achieved by a call processing method which
`automatically processes prescribed communication
`calls from a switching network to a data base system for
`deriving call service information and then returning the
`call to the network for completion in response to the
`information supplied by the data base. In embodiments
`of the method, the information provided by the data
`base is either a destination number, such as for a ma-
`chine message announcement or a station, or a call
`completion authorization code.
`The method is utilized for special service calls, such
`as INWATS calls, served by a communication system,
`such as a local or toll originating screening office or a
`communication customer service system. It involves a
`process of sending a special service call data including a
`dialed number and a suffix code from the switching
`system to a data base system, translating the received
`message into a call control message at the data base, and
`returning the control message to the communication
`system to control the establishment of call connections
`in accordance with the control message. Advanta-
`geously,
`the control message comprises the routing
`message including a number identifying either a subsys-
`tem, such as a voice storage facility, which supplies
`machine messages to the caller, or a called party station
`such as an INWATS customer reservation bureau
`
`which furnishes operator services.
`For INWATS service, each INWATS customer is
`assigned a single ten digit “800” number which is dialed
`by callers on all calls to that customer regardless of their
`place of origination. The number is used to control the
`establishment of connections through a telephone
`switching system to a centralized data base system for
`deriving all of the call routing, traffic measurement and
`network management data on calls to the INWATS
`customer.
`The data is utilized to screen calls for INWATS ser-
`
`vice entitlement and for specifying a directory-unlisted
`POTS (Plain Old Telephone Service) DDD (Direct
`Distance Dialing) number to which entitled calls are
`preferably to be routed to the INWATS customer on a
`
`4
`toll-free basis to the caller. Data is included in the data
`base for specifying the busy/idle status and open/closed
`station condition of the preferred number. An alternate
`unlisted number is also stored in the data base for rout-
`ing calls to that number whenever the preferred number
`is busy or closed.
`The data base is strategically located to serve a multi-
`tude of telephone offices and illustratively is one of
`several designed to serve as call distribution systems for
`the entire United States. It is advantageously arranged
`for traffic measurements of calls to the INWATS cus-
`tomer on the basis of originating area code. These mea-
`surements enable the customer to analyze traffic pat-
`terns and “800” number usage by area code, to obtain
`adequate numbers of INWATS lines and personnel for
`serving the calls, and to determine the economic need
`for the INWATS service in that area. The data base
`
`l0
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`15
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`measures the traffic by counting each call by the origi-
`nating area code and by accumulating a count of all
`calls to the INWATS customer. When the latter ex-
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`ceeds a predetermined threshold per unit time, the data
`base manages the number of calls routed to the pre-
`ferred and/or alternate numbers in such a way as to
`reduce the probability of ineffective call completion
`attempts due to mass calling of the INWATS customer.
`It does so by instructing the telephone system control to
`inhibit calls to the INWATS number for a prescribed
`period of time. This action relieves the telephone voice
`network, data base and CCIS facilities from real time
`involvement on calls to busy stations and makes them
`available for serving other calls.
`table in memory
`The data base comprises a first
`which includes a file of originating area codes (NPAs).
`Each such code is correlated in the file with an individ-
`ual POTS number when INWATS service is purchased
`by the customer for that area code. In response to a
`receipt of a dialed INWATS number and the call origi-
`nating area code from a telephone system, the data base
`examines its NPA file of originating area codes for
`screening the call to check whether the INWATS cus-
`tomer is entitled to receive calls from that area code on
`a toll-free basis to the caller. Entitlement is identified by
`the presence of the POTS number in the same memory
`file as the received area code. The NPA file also com-
`prises a counter which is incremented on each call at-
`tempt per originating area code.
`A second memory table includes an individual file for
`each POTS number that stores busy/idle data and
`open/closed hours information for that POTS number.
`The busy/idle data is dynamically loaded under control
`of the call terminating office signaling the busy and idle
`status of the line(s), or line group, associated with the
`POTS number. The data is advantageously used to
`reduce the probability of ineffective attempts to com-
`plete calls to all busy or closed stations and thereby
`reduces the unnecessary use and tie-up of toll telephone
`switching equipment. It also serves to signal when the
`station is idle and therefore available to serve calls.
`Each POTS file in the second memory table also
`includes an alternate, or second choice, POTS number
`to which an INWATS call is routed when the preferred
`first choice POTS number is either busy or closed. The
`file also comprises a counter which is incremented on
`each call
`involving the preferred POTS number to
`accumulate a count of the total number of calls gener-
`ated. The same file includes threshold and call inhibit
`time data for managing the number of calls that are
`
`

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`4,191,860
`
`5
`directed to the POTS number within a given interval of
`time.
`The procedure for processing an INWATS call com-
`prises a calling party dialing the 800-NXX-XXXX of
`the desired INWATS customer. The local telephone
`office serving the calling station is responsive to the
`dialed number for routing the call
`to a toll office
`equipped with CCIS (Common Channel Interoftice
`Signaling) facilities and sending to that office the dialed
`number. The toll office routinely identifies the area
`code from which the call originates and then sends it, as
`a suffix code, together with the dialed number over the
`CCIS direct signaling system to the data base identified
`by the CCIS system from the dialed 800-NXX.
`At the data base, the received INWATS number is
`checked to ascertain that it is an active working num-
`ber. Next, the file of the originating area code is located
`in the first memory table and the entitlement of the call
`to be made from that originating area is verified by
`extracting the POTS number of the INWATS customer
`station preferably ‘designated to serve the call. The
`NPA file counter is then incremented to indicate a call
`attempt involving the originating area code.
`Thereafter, the file of the preferred POTS number is
`located in the second memory table and the open/-
`closed and busy/idle status of the destination station
`associated with that number is examined. Upon deter-
`mining that the station is open and idle, a CCIS message
`containing the preferred POTS number is sent from the
`data base over the CCIS system to the toll office for
`enabling call connections to be established from that
`office through the toll switching network to the station
`associated with the POTS number. At about the same
`time, the counter in the POTS number file is incre-
`mented to accumulate data on traffic to that POTS
`number and to control call routing to it during mass
`calling periods when the number of calls exceed a pre-
`determined threshold.
`Busy and idle data for each INWATS station is dy-
`namically routed from an associated terminating tele-
`phone office over CCIS facilities to the data base for
`updating records in the file of the station POTS number
`in the second memory table. The busy data controls the
`processing of INWATS cells selectively to alternate
`POTS number(s) and to audible busy station messages.
`The call processing procedure is arranged to return
`CCIS messages from the data base to the toll office to
`identify the dialing of a nonworking INWATS number,
`a call which is not authorized on a toll-free basis from
`that call originating area, and the busy or closed status
`of the INWATS station designated to serve the call.
`The method is advantageously useful for data base
`service on automated collect calling, toll call fowarding
`and other special service calls as hereinafter described.
`BRIEF DESCRIPTION OF THE DRAWING
`
`FIG. 1 shows, in block diagram form, a configuration
`of telephone switching offices, CCIS and signal transfer
`facilities together with one of several data bases illustra-
`tively for serving INWATS calls in the United States;
`FIG. 2 depicts an area code to POTS number listing
`of a data base translator and an originating area code
`call counter;
`FIG. 3 illustrates the data base translator listing of
`busy/idle, closing time, loop, alternate route number,
`and network management data for the POTS number;
`FIG. 4 is a flow chart of data base system operations
`for an INWATS call; and
`
`6
`FIG. 5 is a flow chart of network management opera-
`tions.
`The drawing illustrates a number of local telephone
`switching offices, such as offices 12, 38, 41 and 43 which
`serve associated telephone stations, such as stations 10,
`22, 30 and 31. The drawing also discloses toll offices
`such as offices 15, 34 and 36 which form a toll switching
`network serving the local offices. The structural details
`of such local and toll offices form no part of the present
`invention and are only described herein to the extent
`necessary for an understanding of this invention. Each
`of the local offices, by way of example, is suitably an
`electronic program controlled telephone system of the
`No.
`1 ESS (Electronic Switching System) type dis-
`closed in the Bell System Technical Journal (BSTJ),
`September 1964, Volume XLIII, Number 5, Parts 1 and
`2; and in the R. W. Downing-H. F. May-F. F. Taylor-
`U. Ulrich U.S. Pat. No. 3,570,008 of Mar. 9, 1971. Those
`disclosures and the citations referred to therein may be
`consulted for a complete understanding of the construc-
`tion and operations of a typical local switching office
`12, 38, 41 and 43.
`Each toll office is illustratively an electronic program
`controlled telephone system of the No. 4 ESS design
`with CCIS facilities as disclosed in the Bell System Tech-
`nical Journal (BSTJ), September 1977, Volume 56, No.
`7.
`
`CCIS facilities utilized in conjunction with the local
`and toll offices and the data base system 11 are disclosed
`in the BSTJ, February 1978, Volume 57, No. 2 and in
`W. B. Smith-J. B. Synnott, III U.S. Pat. No. 3,624,613
`of Nov. 30, 1971.
`
`DETAILED DESCRIPTION
`
`In FIG. 1, the processing of a call to an INWATS
`customer is explained by assuming that it is originated
`from a calling station 10 in California. The INWATS
`customer is assigned a single telephone number which is
`dialed by callers on all calls to that customer regardless
`of their place of origination. The number comprises ten
`digits including an 800 area code portion followed by
`seven digits NXX-XXXX. The NXX digits identify the
`data base, such as data base 11 in Texas, which stores
`the INWATS customer data utilized for processing the
`call to the appropriate destination. The NXX-XXXX
`digits identify the INWATS customer within the data
`base. The “N” digit is any value 2-9 and each of the
`“X” digits is any value 0-9.
`For the exemplary embodiment, call processing is
`described by assuming that the call may be routed to
`any one of three destinations, namely, first, second and
`third choice numbers respectively identifying stations
`22, 30 and 31. Each such station is depicted as an indi-
`vidual telephone station for the purpose of illustration.
`It is to be understood that in many cases INWATS call
`answering facilities commercially utilize automatic call
`distributor systems involving numerous groups of in-
`coming telephone lines served by a local or toll tele-
`phone switching system. A typical distributor system is
`disclosed, for example, in S. F. Dunning U.S. Pat. No.
`3,111,561 of Nov. 19, 1963. The three destination sta-
`tions will suffice to explain typical call situations en-
`countering open/closed and busy/idle conditions and
`the likelihood of completing l.NWATS calls in geo-
`graphic areas with different local business hours.
`After station 10 initiates a call and dials the INWATS
`customer number, office 12 recognizes the 800 area
`code and routes the call illustratzively over a trunk 14 to
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`7
`a toll office 15 equipped with CCIS facilities. Office 12
`also forwards the dialed INWATS number to office 15
`for assembly in office 15 with the area code for that
`portion of California from which the call originates.
`Office 15 determines the originating area code based on
`the serving of the call over trunk 14 in a known manner.
`Office 15 routinely translates the dialed 800 digits and
`determines that the call is to be routed to a data base for
`deriving call routing data. As a consequence, office 15
`formulates an INWATS CCIS message including an
`identification of the special service call, the office 15
`and the originating area code as well as the dialed num-
`ber and sends that message over the CCIS link 17 to a
`signal transfer point or system 18. The latter is respon-
`sive to the received message for translating the 800-
`NXX digits to determine that the INWATS customer
`data is stored in the data base system 11, which illustra-
`tively is located in Dallas, Texas. System 18 then for-
`wards the CCIS message to data base 11 over a CCIS
`link 19. System 18 is essentially a data link, or packet,
`switching arrangement for CCIS applications. Packet
`data switching facilities are disclosed for example in A.
`G. Fraser U.S. Pat. Nos. 3,749,845 of July 31, 1973 and
`3,979,733 of Sept. 7, 1976. Structure and operations of
`CCIS are described, by way of example, in the 57 BSTJ
`No. 2, page 230, et seq. Thus, the call is processed from
`the toll telephone switching network to a data base for
`deriving call service information.
`Data base system 11 is, by way of example, a com-
`mercially available system, such as a Western Electric
`Company, Incorporated 1A processor (disclosed in 56
`Bell System Technical Journal No. 7, February 1977),
`equipped with disk storage and a system of programs to
`establish, edit and manage information stored in mem-
`ory. It is equipped via a peripheral unit bus (disclosed in
`57 Bell System Technical Journal No. 2 February 1978)
`with CCIS facilities for interface communication with
`the signal transfer system 18 and the toll network. Sys-
`tem 11 is responsive to the received INWATS number
`and originating area code for deriving all of the stored
`information needed for processing the call to an idle and
`available INWATS customer station designed as the
`preferred called station to serve the call. The informa-
`tion includes data for the active-inactive status of the
`dialed INWATS number, the storage files associated
`with the active number, the inband/out-band character
`of the call based on the received originating area code,
`and a directory-unlisted POTS number of a destination
`subsystem or station.
`For each active INWATS number, data base system
`11 is equipped with translator tables 20 and 21 of FIGS.
`2 and 3. Table 20 contains a list of originating area codes
`and a correlated list of POTS DDD (Plain Ordinary
`Telephone Service Direct Distance Dialing) numbers
`identifying one or more called stations primarily desig-
`nated to serve calls from the respective originating
`areas. Each listed area code is uniquely associated with
`an individual one of the listed POTS numbers when the
`INWATS customer is entitled to receive calls from that
`originating area on a toll-free basis to the calling party.
`A single such POTS number may be shared by a plural-
`ity of different originating area codes. Whenever table
`20 contains a POTS number for an originating area
`code, calls from that area are designated as being “in-
`band”. Otherwise, in the absence of a POTS number for
`the area code, (null entry) calls from that area are “out-
`of-band” for the INWATS customer and calls are not
`completed on a toll free basis to the caller.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4,191,860
`
`8
`Illustratively, on the call originating from station 10,
`the originating area code is 805 and table 20 lists a corre-
`lated POTS number 919-658-3399, which is a called
`station 22 in North Carolina, preferably designated as a
`first choice to serve the INWATS calls. Accordingly,
`such a call is “in-band”. If it were not, no POTS number
`would be listed in table 20 for the area code 805.
`Each originating area code in table 20 is furnished
`with a counter 27 which is incremented on each call
`attempt involving that area code. In this way, statistics
`are derived on calls by area codes regardless of whether
`the INWATS customer purchases the serivce for that
`area.
`
`Table 21 contains a plurality of files each of which is
`associated with an individual POTS number in table 20.
`Each such file, such as file 23, contains eight individual
`items of data for each such number. These data items
`are utilized, as appropriate, for completing calls to the
`associated POTS number and for recording the number
`of such calls for network management purposes. The
`first item 49 is a loop bit used to ensure that the alternate
`routing does not loop on itself. The second item 24
`identifies the times and dates on which the station asso-
`ciated with the POTS number 919-658-3399 is closed or
`personnel
`is unavailable for serving incoming calls.
`Closed times are, for example, nonbusiness hours, such
`as 5 p.m.—9 a.m., holidays, and weekends, such as Sun-
`day. The third item 25 contains a bit indicating the
`current
`busy-idle
`status of
`the POTS number
`919-658-3399. The fourth item 26 contains an alternate
`POTS DDD number 206-582-2044 which is used when
`
`the preferred POTS number is busy, closed or unavail-
`able. The fifth item 46 contains a call counter which
`accumulates a count of the number of calls made to the
`POTS number 919-658-3399 for a current time interval,
`for example, two minutes. The sixth item 47 contains a
`threshold number for inhibiting calls to the POTS num-
`ber. The seventh item 50 indicates whether a network
`
`management control is currently effective based on the
`previous time interval. The last item is a time interval 48
`specifying the period for inhibiting data base inquiries to
`the 800+NXX-XXXX. Entry 48 is dynamically up-
`dated by a procedure described in FIG. 5.
`The utilization of data in tables 20 and 21 and IN-
`WATS information processing operations of the data
`base system 11 are now described for the call from
`station 10 of FIG. 1 with reference to the flow diagram
`of FIG. 4. After the tables 20 and 21 are loaded with the
`
`data as depicted in FIGS. 2 and 3, system 11 is respon-
`sive to the receipt of the CCIS INWATS message for
`checking its records (not shown) to determine whether
`the dialed INWATS number is active or inactive. If it is
`not validly in use and therefore inactive, system 11
`effects a return of a CCIS vacant code message to the
`toll office 15 of FIG. 1 via link 19, signal transfer system
`18 and link 17. Office 15 thereupon routinely causes an
`announcement to be returned to the caller for convey-
`ing dialing instructions and indicating that the dialed
`number is not a working number.
`If the number is active, system 11 examines table 20
`and its file 28 for translating the dialed INWATS num-
`ber and originating area code into a POTS DDD num-
`ber 919-658-3399 by a look-up operation in table 20.
`Next, the area code counter 27 is incremented to indi-
`cate a call from a station in area code 805. Had the
`look-up failed to find such a POTS number (null entry)
`correlated with the originating area code in file 28, the
`dialed INWATS number would be “out-of-band” to
`
`
`
`

`
`4,191,860
`
`9
`that call originating area. Resultingly, system 11 then
`effects an incrementing of a counter 27 and a return of
`an out-of-band CCIS message to toll office 15 of FIG. -1
`via the CCIS links 19 and 17 and the signal transfer
`system 18. Office 15 then routinely effects the transmis-
`sion of a reorder message to the caller.
`System 11 determines that the INWATS call is “in-
`band” when its lock-up operation extracts a POTS
`DDD number 919-658-3399 from file 28. That number
`is then used to locate the file, such as file 23, in table 21
`which contains the eight data items needed for further
`call processing and traffic management. System 11 ini-
`tially checks file 23 to ascertain whether the station
`associated with the POTS number is indicated to be
`open. This is done by examining item 24 of file 23. If the
`station is open, system 11 next examines the busy/idle
`data, item 25. If the station is idle, then the POTS num-
`ber, 919-658-3399 will be returned to office 15 for nor-
`mal call setup. If the station is closed or busy, then
`system 11 examines item 26 of file 23 to obtain an alter-
`nate POTS number. The loop bit, item 49,
`is set to
`prevent looping between POTS numbers. If an alternate
`POTS number exists, such as 206-5 82-2044-, and its loop
`bit is not set, then the process continues until either an
`open and idle station is found, no alternate POTS num-
`ber is found, or transfer is made to a POTS number
`whose loop bit is set. The last two situations will cause
`system 11 to send a CCIS message to office 15, via the
`CCIS facilities, indicating an ineffective attempt. If the
`call results in an ineffective attempt and in the process
`of picking alternate POTS numbers a busy condition is
`encountered, then the CCIS message includes an indica-
`tor telling office 15 to return either a busy tone or audi-
`ble message to the caller. If all encountered POTS num-
`bers had been closed, then the CCIS message includes
`an indicator telling office 15 to transmit an audible mes-
`sage to the caller indicating the status of the called
`station.
`Upon finding that the INWATS call is “in-band” and
`that a station, such as station 22, 30 or 31 associated with
`a preferred or alternate POTS number is opened and
`nonbusy, system 11 effects a transmission of a CCIS
`message including that number to toll office 15 via the
`CCIS facilities 16. Office 15 then controls the establish-
`ment of call connections to the respective station 22, 30
`or 31 illustratively, over trunk 33, toll office 34, trunk
`35, toll office 36, trunk 37, local office 38, and line 39 to
`station 22 or from office 34, trunk 40, local office 41, to
`station 30. Connections to station 31 similarly are ex-
`tendable from office 36 via trunk 42 and office 43. The
`called station is then alerted to the incoming call and
`conversation ensues.
`
`Each file in table 21 is equipped with a network man-
`agement counter which retains a current count of the
`number of calls directed to the POTS number. For
`example, file 32 has the counter 51 for counting calls
`directed to the number 212-525-3333. The last file exam-
`ined in the sequence of first choice or alternate POTS
`numbers increments its current counter item 46. This
`counter will be reinitialized periodically, for example,
`e