(12) United States Patent
`US 6,674,850 B2
`(10) Patent N0.:
`Vu et al.
`
`(45) Date of Patent: Jan. 6, 2004
`
`US006674850B2
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`
`198 04 197 A1
`
`8/1999
`
`......... .. 606F/17/30
`
`* cited by examiner
`Primary Examiner—Harry S. Hong
`(74) Attorney, Agent, or Firm—Wei Wei Jeang; Munsch,
`Hardt, Kopf & Harr, PC.
`
`(57)
`
`ABSTRACT
`
`An optimal digit translation and call processing system and
`method is provided. A prefix translation and digit charac-
`terization process are performed utilizing a digit prefix table
`and a second table interfaced therewith. The digit prefix
`table contains numerous records corresponding to prefixes
`of dialed digit streams. Each record includes an index to a
`record of a second table operable to output a termination
`type of the digit stream. The second table includes numerous
`records associated With various call termination types. Each
`index included Within respective records of the digit prefix
`table may reference more than one record of the second
`table. The digit stream length is analyzed to resolve ambi-
`guities in the digit stream When an index in a record of the
`digit prefix table references more than one record of the
`second table. Multiple records of the digit prefix table may
`have a common index to an identical record of the second
`
`table thus reducing the required number of records in the
`second table for characterizing call termination types. Acall
`screening table is interrogated With termination type data
`obtained from the second table. The call screening table can
`pass call control to a national or international translator table
`Which provide a route index on Which further call processing
`is performed. The route index may be modified by an
`originator routing table, a carrier identification code routing
`table and a time of day routing table before the call is
`ultimately routed.
`
`28 Claims, 2 Drawing Sheets
`
`(54)
`
`(75)
`
`CALL PROCESSING DIGIT TRANSLATION
`AND CHARACTERIZATION
`
`Inventors:
`
`Joe Q. Vu, Plano, TX (US); Matthew
`C. Perry, Plano, TX (US)
`
`(73)
`
`Assignee:
`
`Santera Systems Inc., Plano, TX (US)
`
`Notice:
`
`(*)
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 557 days.
`
`Appl. No.:
`Filed:
`
`09/757,735
`
`Jan. 9, 2001
`Prior Publication Data
`
`US 2003/0165226 A1 Sep. 4, 2003
`
`Int. Cl.7
`
`....................... .. H04M 3/42; H04M 7/00
`
`US. Cl.
`....................... .. 379/220.01, 379/201.01,
`379/207.03; 379/207.11; 379/221.06; 379/221.14
`
`Field of Search ..................... .. 379/20101, 201.02,
`379/20112, 207.03, 207.11, 219, 220.01,
`221.02, 221.06, 221.14
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`........ .. 379/221.02
`* 12/1988 Bogart et al.
`*
`3/1999 Kammath et al.
`........ .. 379/284
`*
`8/1999 Lee et al.
`............ .. 379/221.14
`11/2000 Foelker
`. . . . .
`. . . . .. 379/201.01
`4/2001 Salisbury
`.... .. 379/221.12
`*
`* 11/2001 Alcott
`. . . . . . .
`. . . . .. 379/201.03
`*
`6/2003 Lee .......................... .. 379/242
`
`
`
`4,791,665 A
`5,887,058 A
`5,937,053 A
`6,154,533 A
`6,215,866 B1
`6,324,273 B1
`6,577,725 B1
`
`(21)
`
`(22)
`
`(65)
`
`(51)
`
`(52)
`
`(58)
`
`(56)
`
`AT&T, EXh. 1008, p. 1
`
`016” PREFIX
`TABLE
`110
`
`DIGIT FENCE
`TABLE
`1 20
`
`
`
`3 DIGITS—
`PUBLIC
`FEATURE
`CODE
`
`10 DIGITS-~
`NATIONAL
`
`
`
`AT&T, Exh. 1008, p. 1
`
`

`

`US. Patent
`
`Jan. 6, 2004
`
`Sheet 1 0f 2
`
`US 6,674,850 B2
`
`40
`
`1 00
`
`30
`
`PACKET
`BACKBONE
`
`CODE
`
`DlGlT PREFIX
`TABLE
`1 1 0
`
`DIGIT FENCE
`TABLE
`1 20
`
` 3 DIGITS-
`
`PUBLIC
`FEATURE
`
`SCREENING
`210A CLASS 2100
`
`ZION
`
`FIG 2
`
`7mm:ng
`
`220A
`
`2208
`
`220N
`
`fiwa
`
`AT&T, EXh. 1008, p. 2
`
`AT&T, Exh. 1008, p. 2
`
`

`

`US. Patent
`
`Jan. 6, 2004
`
`Sheet 2 0f 2
`
`US 6,674,850 B2
`
`FIG. 4
`
`PREFIX TREE
`SELECTOR
`
`CALLED
`PARTY ON
`
`TRANSLATION
`GROUP
`
`305
`
`GD
`
`PREFIX TREE
`
`TRANSLATION @
`GROUP
`
`DIGIT FENCE ® 310
`
`INDEX
`
`320
`
`CAUSE CODE
`DIGIT FENCE
`_______ ___‘
`TERMINATION
`I
`TYPE
`CAUSE l
`SCREEN“ @ _ W m'
`
`CALL SCREENING
`
`
`
`CLASS
`
`330
`
`INTERNATIONAL
`DIGIT
`TRANSLATOR
`
`:I
`
`CAUSE!
`
`340
`
`JELLSE901%,:
`ORIGINATOR ROUTING
`____'
`I
`ROUTE a
`,
`INDEX . ® :
`CODE I
`L
`———— —_ ____..I
`g
`
`CIC ROUTING
`
`I
`
`IL
`
`350
`
`ROUTING
`MODIFIER
`
`CARRIER
`ID CODE
`
`345
`
`CARRIER
`
`INDEX
`
`CARRIER
`ID
`
`INDICATOR
`
`GROUP
`DATE
`DAY OF
`THE WEEK
`SUBSCRIBER
`GROUP
`CALL
`ORIGINATION ®
`TIME
`
`DAY OF
`YEAR
`
`ROUTE ®
`
`INDEX
`
`370
`
`360
`TIME
`OF DAY
`ROUTING
`“TIME OF
`INDEX
`TIME OF DAY
`DAY INDEX" @ ROUTING
`ROUTE
`365
`INDEX
`
`315
`
`____ _._i ____ __
`
`_ _ _ _ _ ___.I
`ROUTE I
`I
`INDEX! @
`FFINAL STEP: USE THE FINAL-I
`I
`ROUTE INDEX To ACCESS
`I
`: THE MscRouteUst TABLE To I
`IRETRIEVE THE TRUNK GROUP!
`L_T£)_REUIE_THE SALL_(1N_ J
`ROUTET®
`CALLT
`
`AT&T, EXh. 1008, p. 3
`
`AT&T, Exh. 1008, p. 3
`
`

`

`US 6,674,850 B2
`
`1
`CALL PROCESSING DIGIT TRANSLATION
`AND CHARACTERIZATION
`
`TECHNICAL FIELD OF THE INVENTION
`
`The invention relates to telecommunication switching
`systems and, in particular, to a unified access switch digit
`translation system for providing digit translation and call
`routing in a telecommunication system.
`
`BACKGROUND OF THE INVENTION
`
`Telecommunication carriers are increasingly deploying
`multi-service packages, or bundled services, to customers to
`provide reduced overall access charges in an attempt to
`increase customer retention. For example,
`the boom in
`digital subscriber line subscriptions has led many carriers to
`bundle high bandwidth Internet service with traditional
`voice services. The carrier can advantageously charge a
`higher fee for the bundled service than the individual service
`fees of any of the services that are bundled together while
`still offering a bundled service fee less than the sum of
`typical fees of the individual services thus providing an
`incentive for customers to subscribe to additional services.
`Recent market
`trends indicate an extensive consumer
`demand for these bundled services. Numerous cable carriers
`
`also provide bundled services in the form of traditional pay
`cable television services bundled with high bandwidth cable
`Internet access. Deregulation in the telecommunication
`industry that
`is now allowing long distance carriers to
`compete with local carriers promises to bring additional
`bundled services to the consumer. Wireless services are also
`
`being bundled with numerous combinations of the above-
`mentioned services. Market trends with regard to bundled
`services are unmistakable. Successful carriers of the future
`
`will have the ability to offer various packages of voice and
`data services. Already, carriers are feeling the strain of
`successfully upgrading existing infrastructures to meet the
`high-bandwidth services being demanded by customers.
`Some local carriers are currently reporting up to three year
`back logs of orders for DSL services, for example.
`Transition networks are commonly utilized to provide
`customer access to voice and data networks. An access
`
`network interfaces with voice and data switches each respec-
`tively interfacing with a data network, for example a packet
`backbone network, and the public switched telephone net-
`work. Typically, various classes of voice switches,
`for
`example class 4 switches for providing interexchange carrier
`(IXC) voice services and class 5 switches for providing end
`office voice services, are required within the transition
`network. Multiple media gateways are then required to
`interface with a data access switch. However, work towards
`a truly integrated voice and data network is underway.
`Significant amounts of labor are expended to maintenance
`and upgrade the transition networks as new services become
`available. A move to unified access is clearly advantageous
`and promises to propel emerging technologies that are not
`easily implemented over current large scale networks, for
`example voice over IP (VoIP) and voice over DSL (VoDSL),
`to a broader degree of acceptance.
`Unified access will require greatly improved switching
`systems that are commonly found in the PSTN today. The
`switching fabric will require various services to be switched
`to numerous other disparate networks. For example, a
`inbound time division multiplex message would need to be
`able to be switched to another time division multiple channel
`as well as various other networks, for example IP for a
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`the unified switch
`terminating VoIP customer. Similarly,
`would need to be capable of switching an IP originating call
`to an IP, TDM, frame relay and ATM network, to name just
`a few. Clearly, a switch required to realize unified access will
`have sophistication not embodied in typical switches found
`in carrier networks today.
`Typically, digit translation performed in telecommunica-
`tion switching systems is limited in the amount of servicing
`provided for data networks. A unified access switch would
`preferably be capable of handling translation for all calls
`being translated and routed therefrom. Furthermore,
`in
`today’s switching systems, the lookup tables (referred to
`hereinafter simply as ‘table’) generally have records for each
`termination type capable of being routed from the switch. By
`integrating data services into a unified access switch, the size
`of these tables will undoubtedly grow as services, for
`example screening services, now common with many voice
`services become deployed for data services.
`SUMMARY OF THE INVENTION
`
`In accordance with an embodiment of the present
`invention, an optimal digit translation and call processing
`system and method is provided that reduces the size of the
`tables required for performing digit translation. A prefix
`translation and digit characterization process are performed
`utilizing a digit prefix table and a second table interfaced
`therewith. The digit prefix table contains numerous records
`corresponding to prefixes of dialed digit streams. Each
`record includes an index to a record of a second table
`
`operable to output a termination type of the digit stream. The
`second table includes numerous records associated with
`
`various call termination types. Each index included within
`respective records of the digit prefix table may reference
`more than one record of the second table. The digit stream
`length is analyzed to resolve ambiguities in the digit stream
`when an index in a record of the digit prefix table references
`more than one record of the second table. Multiple records
`of the digit prefix table may have a common index to an
`identical record of the second table thus reducing the
`required number of records in the second table for charac-
`terizing call termination types. In accordance with another
`embodiment of the present invention, a call screening table
`is interrogated with termination type data obtained from the
`second table. The call screening table can pass call control
`to a national or international translator table which provide
`a route index on which further call processing is performed.
`The route index may be modified by an originator routing
`table, a carrier identification code routing table and a time of
`day routing table before the call is ultimately routed.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a more complete understanding of the present
`invention, the objects and advantages thereof, reference is
`now made to the following descriptions taken in connection
`with the accompanying drawings in which:
`FIG. 1 is a simplified telecommunication system includ-
`ing a unified access switch on which the present invention
`may be deployed;
`FIG. 2 is a simplified digit prefix table and digit fence
`table for performing digit prefix characterization including a
`termination type analysis;
`FIG. 3 is a simplified screening table according to an
`embodiment of the present invention; and
`FIG. 4 is a flowchart of the prefix translation and digit
`characterization process of the present invention including
`call screening and routing processes thereof.
`
`AT&T, EXh. 1008, p. 4
`
`AT&T, Exh. 1008, p. 4
`
`

`

`US 6,674,850 B2
`
`3
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`The preferred embodiment of the present invention and its
`advantages are best understood by referring to FIGS. 1—4 of
`the drawings, like numerals being used for like and corre-
`sponding parts of the various drawings.
`In FIG. 1, there is illustrated a simplified telecommuni-
`cation system 100 including a unified access switch 10
`according to the present invention. The unified access switch
`10 provides an interface for an access network 20 to, for
`example, a packet backbone network 40 and the public
`switched telephone network (PSTN) 30. The access network
`20 may interface to various telecommunications equipment,
`for example asynchronous transmission mode, frame relay,
`and Internet protocol devices all generally designated by
`reference numeral 50, as well as an integrated access device
`(IAD) 60, private branch exchanges (PBXs) 70, and digital
`loop carriers (DLCs) 80, operating under disparate protocols
`and transmission techniques. The unified access switch 10
`provides interfacing of subscriber lines to switching hard-
`ware and software for connection to other subscriber lines
`and communication facilities.
`
`The unified access switch 10 preferably includes various
`protocol
`translation modules that may be embodied in
`various hardware and software. Pursuant to providing digit
`translation according to the present invention, various tables
`are maintained within the unified access switch 10. These
`
`tables are preferably stored within memory modules within
`the unified access switch 10. The tables may contain numer-
`ous records each respectively storing various parameters and
`identifier fields respectively associated with and defining
`various subscriber services. It should be understood that the
`term table as used herein is not intended to limit the data
`contained therein to traditional record-field table formats but
`
`for
`may include data stored in various tree structures,
`example, for facilitating data searches thereof. A database of
`subscriber profiles is preferably maintained within the uni-
`fied access switch 10 and defines various services subscribed
`
`to by the subscribers. These services may define appropriate
`routing procedures for respective call termination types and
`may be associated with voice as well as data services calls.
`The subscriber profiles are preferably maintained within
`read-write memory modules for facilitating modification of
`the data, that is the subscription services, defined therein.
`Preferably, each of the subscriber profiles include a prefix
`tree selector, a translation group, a screening class, a carrier
`identification and a subscriber group although the informa-
`tion contained within each of the subscriber’s profile is not
`limited thereto.
`
`The call processing digit translator of the present inven-
`tion includes a dialed digit recognition module, a dialed digit
`classification module, a call termination screening module
`and routing module. The digit
`translator provides digit
`recognition and interpretation capabilities and, based on the
`digit recognition and interpretation functions, determines
`how the call is to be processed, for example routed though
`the network, denied access, etc. The digit translator is a
`programmable translator that can be configured to handle
`various call scenarios in the emerging integrated voice and
`data services switches. The digit
`translator is advanta-
`geously programmable and accordingly can provide call
`processing for services currently being offered and future
`services yet to be deployed.
`Digit translation according to the present invention is
`performed universally on all call originations, regardless of
`whether these calls are subscriber line originated calls or
`trunked originations. Furthermore, the translator is adapt-
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`able to process call originations irrespective of the protocol,
`the call features invoked by the call and customer specific
`data included in the call origination.
`The call processing digit translation and call processing of
`the present invention is performed in three general steps and
`includes a prefix translation and digit prefix characterization
`step, a call screening step and a routing step. Each of these
`steps is carried out by interrogation of various tables main-
`tained within the switch. Generally, the prefix translation
`step is implemented to recognize pre-designated calling
`prefixes. When the prefix translation step determines pre-
`designated calling prefixes exist in the digit stream,
`the
`pre-designated prefix is removed from the stream. The called
`party (destination) number is then recovered from the
`remaining stream. The final call type, that is the termination
`type, is then evaluated from the digit stream. Finally, the
`digit stream is analyzed for ambiguously dialed number
`combinations.
`
`The call screening step is generally implemented to
`determine whether the originating (calling) party is allowed
`to perform the call under the evaluated scenario. Ascreening
`class associated with the call originator is retrieved from a
`subscriber profile maintained on the originating party.
`Generally, each calling party accessing the switch for origi-
`nating a call therefrom will have a subscriber profile main-
`tained within the switch describing the originator’s subscrip-
`tion services. The originator’s profile may include various
`data relating to call services of the subscriber and includes
`any call screening functions and special routing services
`subscribed to by the originator. The termination type, as
`evaluated in the prefix translation and digit prefix charac-
`terization step, is then compared with the screening class to
`determine if the call is allowed. If the call screening step
`affirms that the originating party is allowed to place the call,
`a routing step is implemented for refining the call type
`analysis and evaluating a route for trunk terminated calls.
`Screening services for voice and data services may be
`distinguished by the screening class, for example, or other
`subscriber data such as the subscriber group.
`The call processing digit translator of the present inven-
`tion is preferably implemented in various computer execut-
`able code modules, or application programming interfaces,
`maintained with the unified access switch 10 of the present
`invention. Two data tables are accessed by the prefix trans-
`lation of the present invention.
`Adigit fence table contains data to characterize the dialed
`number. The digit fence table includes a fence index field for
`identifying various records therein. A digit prefix table
`contains a list of prefixes each having an associated digit
`fence table index. These two tables are used, in conjunction
`with one another,
`to recognize and separate any special
`prefixes, for example prefixes used for designating an invo-
`cation of public features,
`to determine the called party
`number. The digit fence table and the digit prefix table are
`collectively utilized to determine the general nature of the
`called number and resolve any ambiguously dialed number
`as well.
`
`A prefix translation module, or prefix translation API,
`provides initial call screening and digit manipulation by
`accessing the digit fence table and a profile associated with
`the calling originator. The dialed digit prefix may be clas-
`sified according to various defined prefixes, for example a
`standard prefix such as *, 101, 0, 1, etc., a directory prefix
`number, an international number, etc. By using two tables to
`specify the prefix and identify the call type, two distinct
`advantages are realized. Multiple, identical prefixes entered
`
`AT&T, EXh. 1008, p. 5
`
`AT&T, Exh. 1008, p. 5
`
`

`

`US 6,674,850 B2
`
`5
`in the prefix translator table can be mapped to an identical
`index of the digit fence table. Repetition in the digit fence
`table is therefore reduced. Furthermore, multiple entries in
`the digit fence table can be selected with a single index of
`the digit fence table. Different entries sharing a digit fence
`index represent different ambiguous numbers that,
`for
`example, start with a common prefix. The particular digit
`fence index used for a call is selected based on the dialed
`
`digit length. Thus, various digit fence indices may corre-
`spond to a common prefix with each of the records of these
`different indices corresponding to dialed digits of differing
`lengths.
`The functional behavior of the digit prefix table, also
`referred to herein as a prefix tree, as it interacts with the digit
`fence table may be better understood with reference to FIG.
`2. The digit prefix table 110 includes numerous entries, for
`example prefix entries 110A—110N respectively illustrating
`the entries for *66, 214, *69 and 972 prefixes, for the various
`valid prefix entries that may be recovered from an originat-
`ing phone call digit stream. It is understood that the prefix
`entries 110A—110N are exemplary only and numerous such
`prefixes exists. Furthermore, the prefixes included in the
`digit prefix table 110 are preferably dynamic in number, i.e.
`the digit prefix table 110 is updateable such that prefixes
`addressing as yet undeployed services or prefixes addressing
`yet-to-be defined calling area codes, may be added to the
`digit prefix table 110 when desired.
`An example of multiple prefixes having a common digit
`fence table index, as mentioned above, is illustrated in FIG.
`2. For example, prefixes *66 and *69 having respective digit
`prefix table 110 entries 110A and 110C share a common digit
`fence table index and are accordingly mapped to the digit
`fence table entry 120A that designates a public feature code,
`that is digit prefix table entries 110A and 110C both include
`an identical index referencing the digit fence table entry
`120A. Furthermore, the digit prefix table entries 110B and
`110N respectively associated with prefixes 214 and 972
`share a digit fence table index and are thus commonly
`mapped to entry 120N of the digit
`fence table 120.
`Generally, most numbering plan areas (NPAs) can share a
`common profile and thus a common digit fence table index.
`Furthermore, each prefix entry of the digit prefix table 110
`may be mapped to multiple digit fence table 120 entries.
`Thus, a single digit fence table index may be used to
`reference multiple entries of the digit fence table 120.
`Multiple mappings from a single digit fence table index may
`be performed by analyzing the digit string length and
`mapping the index to a digit fence table entry accordingly.
`Such a procedure may be used to resolve ambiguous digit
`streams as described more fully below. Providing multiple
`mappings from a single digit fence table index reduces the
`number of required entries in the digit prefix table 110 by
`eliminating the need for separate entries in the digit prefix
`table 110 for identical prefixes having different termination
`types, for example national and international termination
`types having a common prefix.
`As a further aspect of the present invention, the digit
`prefix table 110 and the digit fence table 120 may be
`conjunctively used to resolve ambiguously dialed numbers,
`for example numbers having a common NPA and central
`office number That is, in a dialed number having the
`form NPA-NXX-XXXX where NXX designates the specific
`telephone company central office, an ambiguity results when
`the NPA and NXX are identical. In the present invention,
`ambiguously dialed digits are resolved by exploiting the
`ability of assigning multiple digit fence entries to a common
`digit fence index. For example, consider a case where the
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`NPA and NXX digits are both 972. A dialed digit stream
`having an NPA of 972 would take the form of 972-NXX-
`XXXX. A dialed digit stream having an NXX of 972 would
`be of the form 972-NXXX. Both numbers can be recognized
`by the common prefix, in this case 972. However, for proper
`call routing, different results should occur depending on the
`dialed digit string length. Two entries are made in the digit
`fence table each sharing a common index to resolve the
`ambiguity. A first entry, corresponding to the dialed digit
`stream having an NPA of 972, would classify the dialed digit
`stream as national (10 digit dialed digit stream) thus requir-
`ing no digit stream modification. A second entry, corre-
`sponding to the dialed digit stream having an NXX of 972
`(7 digit dialed digit stream), would classify the number as
`national along with a need to prefix the NPA on the digit
`stream. The prefix translator table 110 is used to produce the
`digit fence index when the 972 prefix is recognized. The
`index is then checked against the digit fence table 120 to find
`the two entries. The actual number of digits dialed is used to
`determine which profile is used. Other NXX combinations
`having an equivalent NPA sequence of numbers are resolved
`in a similar manner.
`
`Digit prefix characterization generally proceeds to one of
`a number of defined results. In general, the prefix is char-
`acterized as a public feature code, a national or international
`prefix, 911, operator assistance, or a special number, for
`example a service area code (SAC) such as personal com-
`munication services (PCS), toll services and premium ser-
`vices. Additional prefix characterizations include user-
`specified cause values that result
`in user-defined call
`treatments, for example an assigned tone, a user-defined
`announcement or an intercept route. Asystem-defined cause
`value results when a failure to match the digit prefix occurs.
`The translation process terminates if a cause value is
`assigned.
`The unified access switch 10 of the present invention
`preferably utilizes a separate table for performing call
`screening. With reference to FIG. 3, there is illustrated an
`embodiment of a screening table 200 preferably maintained
`within the unified access switch 10 of the present invention.
`The screening table 200 is utilized to verify that the origi-
`nating calling party is allowed to perform the type of call
`being placed. A screening class 210B stored within the
`originator’s profile is compared with a termination type
`220C assigned by the digit fence table 120. Results of the
`comparison between the screening class and the termination
`type indicate call allowance or disallowance. Numerous
`combinations of call types can be disallowed by the screen-
`ing class table 200 based on the various termination types
`that can be assigned by the service provider. Consequently,
`numerous screening classes 210A—210N may be defined to
`exploit the variety of termination types 220A—220N, for
`example national termination types, international termina-
`tion types, and SAC termination types, defined by the
`service provider.
`Comparisons may also be made during call screening to
`determine if the dialed digits are valid pursuant to prohib-
`iting call processing and routing that would be wasted
`processing resources on an invalid terminating number.
`Interrogations may also be performed to determine if the
`calling originator is pre-subscribed to the carrier when
`carrier specified dialing is performed. In the event that the
`originator is not pre-subscribed with the carrier, call pro-
`cessing may then proceed according to the carrier’s specified
`treatment of non-subscribed parties. Additionally, the pres-
`ence or absence of a toll prefix, for example 1+(NPA NXX
`XXXX), may be evaluated against the originator’s profile to
`
`AT&T, EXh. 1008, p. 6
`
`AT&T, Exh. 1008, p. 6
`
`

`

`US 6,674,850 B2
`
`7
`determine if toll calls are allowed from the originating party.
`Two commonly implemented screening classes may include
`toll blocking, for example blocking 1+NPA NXX XXXX
`dialed number in order to prevent long distance charges from
`the originator, and premium call blocking, for example
`NPAs of 900 and 976 that result in fees not associated with
`long distance or carrier charges. By enabling a 1+ call
`blocking in the originating party’s profile, the call is disal-
`lowed if a 1+ prefix is isolated during prefix translation.
`Likewise,
`the call
`is disallowed if a premium blocking
`record in the originator’s profile is maintained and an SAC
`premium prefix is isolated during prefix translation. In the
`event that a call is screened, a user-defined cause value
`specific to the call disallowance may specify appropriate call
`treatment, for example generation of a tone or an announce-
`ment that is played to the calling originator.
`A national digit translation table is preferably utilized by
`the unified access switch 10 of the present
`invention.
`National numbers dialed by an originating party are com-
`pared with entries of a national digit translation table to
`determine a corresponding entry therein. Numbers com-
`pared with entries of the national digit
`translation table
`should be unambiguous as a result of prefix translation as
`described hereinabove with reference to FIG. 2. Entries in
`
`the national digit translation table can be any length of
`digits. However, digit lengths preferably include the NPA
`and NXX digits, or more, to allow for office code validation
`and an analysis of the local number portability. Failure to
`recover a matching national digit entry in the national digit
`translation table results in a call failure treatment. Successful
`
`recovery of an entry from the national digit translation table
`produces an index utilized for performing call routing in
`conjunction with an origination based routing table
`described more fully hereinbelow.
`A country code table is preferably utilized by the unified
`access switch 10 of the present invention to provide inter-
`national digit translation. The digits following the interna-
`tional prefix are verified by interrogation of the country code
`table. Failure to recover a valid country code from the
`country code table results in generation of a cause code that
`directs the unified access switch 10 to perform a call failure
`process. If a country code is successfully recovered from the
`country code table, the remaining digit length is compared
`against the identified country’s dialing plan. If an appropri-
`ate entry fails to be recovered for the identified country’s
`dialing plan, a cause code directing the switch to process the
`call as a call failure is produced. If both the country code and
`the remaining digits of the dialed number are successfully
`matched with respective entries in the country code table, an
`initial routing index is returned that is used in conjunction
`with an origination-based routing table as described more
`fully hereinbelow.
`An origination-based routing table is preferably utilized
`by the unified access switch 10 of the present invention to
`provide an updated route index based on an origination
`routing modifier obtained from the originator’s profile. The
`origination routing modifier obtained from the originator’s
`profile is compared with an initial route index to further
`refine the digit classification (digit type). The comparison
`results in an updated route index. Refinement of the digit
`classification is performed on all digits that have been
`classified in the prefix translation as national numbers. These
`numbers are refined to provide local subscriber numbers,
`intra-local access and transport area (intraLATA) and inter-
`local access and transport area (interLATA) numbers. Route
`action types are included in the origination-based routing
`table and provide an indication of whether carrier routing is
`
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`15
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`20
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`25
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`35
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`8
`to be performed. For example, a route action type of ‘route
`immediate’ will cause a carrier routing step to be bypassed.
`Carrier routing may be invoked by a route action type of
`‘route by carrier’. A route action type of ‘treatment’ may
`result for alternative routings, for example failed call treat-
`ment or subscriber specified routings.
`A carrier identification (CIC) table, as well as CIC routing
`table, are conjunctively utilized to provide appropriate rout-
`ing of the call. A carrier ID code assigned to the call is
`utilized to control routing of the call. The carrier ID code
`may be included within the subscriber’s profile or may be
`included within the call setup by the unified access switch
`10. The particular carrier ID code assigned to the originator
`defaults to either one of two primary interexchange carriers
`(PICs). The digit type of the call, as determined from the
`origination-based routing table, determines which of the
`PICs is to be utilized. The default PIC may be overridden by,
`for example, including an originator specified carrier in the
`original call setup message or connection admission control
`message. Additionally, the digit fence table 120 may include
`data indicting an originator specified carrier to provide an
`override of the default PIC.
`
`A carrier ID code is indexed in the CIC table to provide
`a carrier index for the call. The carrier index and the route
`
`index, as obtained from the origination-based routing table,
`are input into the CIC routing table. Results from the CIC
`routing table may include various types of routing to be
`performed including immediate routing, t