Method of Determining End-of-Dialing for Cellular Interface Coupling a Standard Telephone to the Cellular Network

The present invention is directed to software and method of determining the end-of-dialing of a telephone number made on a standard, land-type telephone coupled to a cellular network via a cellular interface apparatus. Cellular interfaces that couple a standard, land-type telephone, such as a POTS (Plain Old Telephone System) phone or facsimile machine, and the like, to a cellular network are disclosed in commonly-owned U.S. Pat. Nos. 4,658,096, and 4,737,975, which patents are incorporated by reference herein. The prior-art cellular interface systems determine when the last digit of a telephone number has been dialed, or entered, based on three methods: Digit count, time-out, and manual send. In the digit-count method, the apparatus automatically counts the number of digits dialed, and upon reaching a preset limit, will trigger an automatic SEND signal to send the telephone number to the transceiver for completing the call over the cellular system. This method also relies upon digit recognition, such that, if the digit 1 is dialed first, the apparatus will know to wait for the input of eleven digits before triggering the automatic SEND signal. The problem with this method is that the count of digits for which the automatic SEND signal is triggered will typically vary from one country to another, and requires relatively sophisticated software.

The second method, time-out, relies upon a preset lull after the dialing of a digit, and if that preset lull has been reached, it is automatically assumed that the last digit of the telephone number has been entered, and the automatic SEND signal is then generated. This method suffers from the drawback that the generation of the SEND signal is relatively much longer after the entry of the last digit as compared switch the first, digit-count method. The lull time-out may run from two seconds up to twenty seconds. The programmable timer of this method is circuitry which has user or factory-adjustable parameters. The time-period is factory set to a value, nominally 3 seconds, and is stored in the radio EEPROM. Depending on customer requirements, it can be set over a wide range of delays (typical values have been from 2 to 10 seconds). If the value is set too long, the customer may wonder why the phone is waiting; if it is set too short, the phone will mis-dial with an incomplete number, if the customer pauses too long.

The third, manual method relies upon the user of the telephone to press a predetermined "SEND" button on the telephone, such as the pound key or star key, or the like, after having entered the last digit of the telephone number, in order to activate the SEND signal. An alternative version of this is the use of a hook flash which will cause immediate generation of a SEND command. The timing of a hook flash is elusive to many people. If it is too quick, it is not recognized by the system; if it is too long, the telephone will hang up.

According to the present invention, a new method is used, in conjunction with one or more of the three prior-art methods outlined above, for accelerating the generation of the automatic SEND signal for those telephone numbers that have been previously dialed on the telephone.

It is the primary objective of the present invention to provide a method for use with a cellular interface that couples a standard, land-type telephone, such as a POTS phone or facsimile machine, or the like, to a cellular network that will automatically generate a SEND signal upon the matching of the dialed telephone number with a previously-dialed telephone number stored in the memory of the cellular interface unit.

It is a primary objective of the present invention to compare the dialed telephone number to the list of previously-dialed, stored telephone numbers by storing the previously-dialed telephone numbers by numerical order, by time-ordering or other technique.

It is another objective of the present invention to automatically allow one of the prior-art, end-of-dialing methods to determine the generation of a SEND signal for those dialed telephone numbers that are not matched with a stored, previously-dialed telephone number.

It is another objective of the present invention to store a previously-dialed telephone number, for matching to a presently-dialed telephone number, allowing it to be automically sent to the transceiver after it has been previously dialed at least one or more times.

Toward these and other ends, the method of the present invention consists of software stored in the memory of a cellular interface unit that couples a standard, land-type telephone, such as a POTS phone or facsimile machine, to a cellular network. The software of the invention will automatically generate a SEND signal to the transceiver upon the matching of a presently-dialed telephone number with a previously-dialed telephone number stored in the memory of the cellular interface unit. The software of the invention stores the list of previously-dialed telephone numbers by numerical order, by time-ordering, or random storage of numbers, and continually updates the list for each new dialed telephone number that is dialed on the telephone of the system. The software of the invention will allow one of the prior-art, end-of-dialing methods to determine the generation of a SEND signal for those presently-dialed telephone numbers that are not matched with a stored, previously-dialed telephone number a preset number of times, such as two.

The invention will be more readily understood with reference to the accompanying drawing, wherein:

FIG. 1 is a flow chart showing the initialization from system reset of the matching process of a presently-dialed telephone number with a stored list of the previously-dialed telephone numbers;

FIG. 2 is a flow chart showing the initialization for the start of a new dialing sequence for matching a presently-dialed telephone number with a stored list of the previously-dialed telephone numbers;

FIG. 3 is a flow chart showing the actual matching process of a presently-dialed telephone number with a stored list of the previously-dialed telephone numbers; and

FIG. 4 a flow chart showing the sequence of events for determining the storage and deletion of a previously-dialed telephone number.

The present invention consists of software stored in the memory of a cellular interface that couples a standard, land-type telephone, such as a POTS phone or facsimile machine, to a cellular network. The software of the invention is based on an algorithm which will provide, without user-intervention, rapid comparison of the number currently being dialed to a set of numbers previously dialed and stored in memory. When the algorithm determines that the currently-dialed number matches a previously-dialed number that had a high probability of call completion, a SEND command will be issued. This algorithm distinguishes between confusingly similar numbers. The purpose of the algorithm is to recognize the end of dialing of a telephone number currently being dialed, and it is not used to complete the dialing of a number, such as partially-entered number, nor is to serve as a "speed-dial" table. The software of the invention utilizes the algorithm for matching the entire, currently-dialed telephone number to the list, or table, of stored, successfully-completed, previously-dialed, telephone numbers. If the currently-dialed telephone number has no match in the table, then one of the prior-art methods of determining the end-of-dialing is utilized for generating the SEND command for transmitting the currently-dialed telephone number to the transceiver.

In order to determine if a telephone number is to be stored as a successfully-completed, previously-dialed, telephone number, certain preconditional criteria must be utilized. According to the invention, all number sequences acceptable to the telephone storage system of the invention are non-redundant, i.e., no number can appear as a leading subset of another number. For example, if "234 5678" is a valid telephone number for storage in the table, then "234 567 8901" cannot be a valid telephone number, since the software of the invention will never be able to get beyond the first seven digits. (This is why dialing "1" for long distance was added in the PSTN.) Therefore, "1 234 567 8901" is a valid and non-redundant telephone number, and may be stored in the table according to the present invention. Thus, there is no need to differentiate international from local telephone numbers, since all numbers are nonredundant sequences. Tne exception to this rule is the digit "0", which may be used alone to dial the operator, or may precede a longer string of digits; the system of the invention requires a minimum number of digits, thus preventing recognition of a single "0" as a valid number.

The method of the present invention may be turned off or on by the user via entry of a specific key sequence. When off, the status of all stored numbers is retained, and no new numbers are entered.

A list of N successfully-completed, previously-dialed, telephone numbers will be stored in memory, where N may be set to any number depending on the amount of memory available and the speed of the processor. Because storage is finite, an indication of the "age" of the telephone number (number of other numbers dialed since the current telephone number was last dialed) is necessary, in order to indicate which telephone number is oldest and should be deleted when space must be cleared in order to add a new telephone number.

The storage of the telephone-number table will be preferably in NVRAM (non-volatile RAM), but is not critical. However, usually, RAM will be more readily available than NVRAM, and may be used for storage. Loss of power will delete the list of memorized numbers. A manual reset, that effectively empties the stored list of telephone numbers, may also be provided. Since the length of telephone numbers varies across the world, and since there are no limitations on where a phone may be used, no scheme to count digits is implemented, other than an optional requirement of a factory-programmable, minimum number of dialed digits, in order to help prevent invalid-number memorization. Each telephone number is to be stored in the list, or table, only once. A count of the number of times the telephone number has been successfully dialed (up to a maximum, or MIN-HITS) will be included in the list or table. Declaration of end-of-dialing (EOD) via the method of the present invention is not valid until the number of times dialed count equals a minimum amount or MIN-HITS, where MIN-HITS will be at least 2, and where each time the telephone number was dialed ended in a successful transmission. This restraint, where the number of times dialed count must be equal or greater than MIN-HITS, will prevent an incomplete telephone number from being falsely acquired and stored in the table, which otherwise could occur, for example, if, by waiting too long between dialed digits, the time out EOD method would kick in; thus, because the software of the invention could never get past the falsely shortened number once it has been acquired into memory, the use of T equal to or greater than 2 will solve this problem, in addition to the previously-mentioned requirement of a factory-programmable, minimum number of dialed digits. This is necessary, since a falsely-shortened telephone number can violate the assumption that numbers are nonredundant.

If it is possible to determine from the telephone that a voice/traffic channel is assigned, a new number may be further qualified. The new number will only be stored if a voice/traffic channel is assigned by the network for a predetermined amount of time (15 seconds or so). If a number is explicitly rejected by the network, and only control messages are exchanged, the number will be declared invalid and not enter the table. If the particular type of phone is unable to communicate this information to the processor on which the algorithm runs, this qualifier cannot be implemented.

Each number stored in the table-memory will be followed by an automatically-appended character, for example, "#", that flags the end of the number.

As mentioned above, numbers may be stored randomly, in number-sorted form, or time-ordered form. The preferred form of the invention is random-storage. In the case of random or number-ordered storage, another field is required, which additional field is a "tag" to indicate "age" information, so that the oldest, stored telephone number may be eventually discarded as a new one is added. In the time-ordered method, the oldest telephone number will fall off, or be deleted, when the end of the memory capacity has been reached and a new telephone number is to be acquired. Under the time-ordering method, when the dialed telephone number has been recognized as a previously-stored number, the old instance of that previously-stored telephone number must be removed, with that same telephone number now being stored at the head of the list.

In the preferred embodiment, the memory of the cellular interface unit, is used as follows. RAM locations are used to store the incoming, currently-dialed, telephone number sequence. RAM locations are used to store the table or list of previously-dialed telephone numbers. The number of times (T) the telephone number must be dialed before being declared valid for entry into the table, where it is available to indicate EOD, is hard-coded with the software program code. RAM location or register is, also, used to store the count of the digits being currently dialed (digit index). In addition, each stored-number location of the table of stored, previously dialed, telephone numbers in RAM includes space for a telephone number up to, preferably, 16 digits, the number of times that number has been previously dialed, an age indicator, and a flag indicating a match up to the current digit with the number being dialed.

Referring for now to FIGS. 1-4, there are shown the flow charts for the preferred form of the invention, where the list of stored, previously-dialed telephone numbers is stored in random fashion. FIG. 1 shows the reset process 10. All of the telephone number entries are set such that their age-indication is at a maximum, with the number of hits at zero, and the dialed telephone number at null, whereby there are no stored telephone numbers stored in the memory-table (block 12). At this point, the system has yet to be used for the first time, or the system has been reset by cutting of power to the system, or by resetting it via a key-sequence input. The "reset" subroutine then exits (block 14).

FIG. 2 shows initialization process 20 that occurs before each telephone number is dialed when a dial tone starts (off-hook condition). After dial-tone generation by the cellular-interface unit that couples a standard, land-type telephone, such as a POTS phone or facsimile machine, and the like, to a cellular network, such as that disclosed in U.S. Pat. Nos. 4,658,096, and 4,737,975, the software of the invention clears the dialing buffer, sets the digit position count to zero, and sets the "Table Index" to "Not Found" (block 22). To ensure that all of the previously dialed telephone numbers stored in the tablememory are searched and compared to the currently-dialed telephone number, each entry in the table has its match-flag set to "true" (block 24), upon which ii the dial-tone subroutine exits (block 26), and the software of the invention awaits the entry of the digits of a telephone being dialed.

Referring now to FIG. 3, the actual, "Dialed Digit Matching" subroutine 30 is shown. In decision block 32, the dialed digit position is first examined to see if it is greater than the maximum allowed. For example, if the currently-dialed telephone number is greater than 16 digits, then upon the entry of a 17th digit ("NO" of decision block 32), then the subroutine exits (block 34), and the matching process for the currently-dialed telephone number is terminated, with the one of the other EOD methods being then employed to generate the SEND command, such as the time-out method. If the dialed digit is in a location that is less than the maximum allowed ("YES" of decision block 32), then that currently-dialed digit of the currently-dialed telephone number is stored in the dialing buffer area of RAM (block 34). After each digit of the currently-dialed telephone number has been stored in the dialing buffer of RAM, then that digit and its value is checked against the list of previously-dialed telephone numbers to see if there is a match (block 36). If the digit is the first one dialed, then all of the previously-dialed telephone number entries in the table are searched and compared; that is, for first dialed digit, all of the entries of the table have been initially set to have a match-flag of "TRUE". Thus, for the first digit entry, the answer to decision block 38 will be "YES" for each entry of the table. In block 40, the dialed digit is compared to the corresponding digit of each table-entry. For the first dialed digit, all table-entries will be searched; for subsequent dialed digits, only those entries for which the "Match Flag" has been set to "TRUE" will be searched. If the entry is not found to match, then the answer to block 40 is "NO", the matchflag for that entry is set at "FALSE" (block 42), and then the subroutine checks to see if all of the entries have been checked (block 44), and if "NO", then the next entry is selected (block 46), and the process repeated. If the answer to decision block 44 is "YES", meaning that all of the entries have been compared, then the subroutine exits (block 48), and returns to decision block 32 and awaits the entry of the next dialed digit, whereupon decision block 32 will again determine if its location is less than the maximum allowed, and if "YES", then blocks 34-40 are repeated for each dialed digit. If the answer to decision block 40 is "YES", which means a match has been found between the dialed digit and the corresponding digit in the table-entry, then the subroutine checks to see if the next digit position of the table-entry is the terminator symbol, such as "#", or the like (decision block 50). If "YES", then this indicates that the dialed telephone number is the same as the table-entry just checked (block 52). If the answer to decision block 50 is "NO", then the subroutine advances to decision block 44 to see if all of the entries have been compared. If all have been checked, then the subroutine exits (block 48), and returns to decision block 32 to await entry of the next dialed digit of the currently-dialed telephone number. If not all of the entries have been checked, then the subroutine returns to decision block 38 to check the next table-entry.

If the answer to decision block 50 is "YES", the subroutine has determined that the currently-dialed telephone number matches one of the entries. The program then sets "Table Index" to the matching entry (block 52), then the program determines how many times that table-entry has been successfully dialed out; that is, in decision block 54, the subroutine determines if the minimum number of times dialed (MIN-HITS) is at least equal to some minimum of prior, successfully-completed calls for that table entry, which is preferably equal to or greater than 2. If "YES", then the EOD flag is set as "TRUE" (block 56), and the "SEND" command is caused to be generated. If the answer to decision block 54 is "NO", meaning that the table-entry has only been successfully called once, if T=2, then the subroutine will disregard this table-entry and advance to decision block 44 to again see if all table-entries have been compared. Since, for all intents and purposes, there has been a complete match to a table-entry, but that the value of T has not yet been reached, the subroutine will advance to exit immediately (block 48), and the currently-dialed telephone number will have its "SEND" command generated by one of the prior-art methods, such as the time-out method.

Referring now to FIG. 4, there is shown the subroutine for determining whether a currently-dialed telephone number should be newly added to the table of previously-dialed telephone numbers, as well as other updating functions therefor. The subroutine in FIG. 4 first determines how long the currently-dialed telephone number was connected (block 60). If less than the minimum time, such as 15 seconds, then the call is assumed to have no importance. If the call was connected for more than some minimum time, then the subroutine begins. The subroutine in FIG. 4 first ensures that the currently-dialed telephone number has at least a required amount of digits (decision block 62), in order to prevent the storage of misdialed numbers in the storage table. If "NO", then the subroutine exits (block 64). If "YES", then the subroutine continues to determine if the currently-dialed telephone number has found a match in the table of entries of previously-dialed telephone numbers (block 64). If "NO", indicating the currently-dialed telephone number has found a match with a previously-dialed telephone number in the table of entries, then the currently-dialed telephone number is selected for entry in order to update the table (block 66). Decision block 68 then determines how many times the previously-dialed telephone numbers matched to this currently-dialed telephone number has been successfully dialed out, or the number of "hits". If the number of "hits" is greater than the minimum amount (greater than T, where T is preferably equal to or greater than 2), then the answer to decision block is "NO", and the subroutine advances. If the answer to decision block 68 is "YES", then the subroutine will increment the number of successfully completed calls, or hits, in RAM for that entry (block 70). In either a "YES" or "NO" to decision block 68, the subroutine advances to block 72, where the age of all entries are incremented, such that each entry, besides the current entry, will have its time stamp updated or incremented by one to a greater value, for all those previously-dialed telephone numbers in the table whose time stamps were more recent than the previous time stamp of the matched previously-dialed telephone number. The currently-dialed telephone number, which is the matched previously-dialed telephone number, will now have its time stamp updated and set to zero (block 74), indicating that this entry is the most recent entry.

If the answer to decision block 64 is "YES", indicating that it is the currently-dialed telephone number that has found no match in the table of entries, then the table of entries must be updated by replacing the oldest previously-dialed telephone number with the newest, currently-dialed telephone number (blocks 76 and 78). The value of the number of "hits" for this newest entry is set at 1, since it is the first time this currently-dialed telephone number has been successfully dialed out (block 80).

The following is the software listing for performing the above-detailed flow charts. It is noted that this software will operate on a table whose entries have been stored using a non-ordered method.

While the radio network and interface discussed hereinabove have been those for the cellular network, other radio network systems may also readily employ the system of the invention. The types of cellular-like systems, besides the pure-type of cellular systems, in which the present invention may be used, are those that relate generally to a wireless digital personal communications systems having a plurality of intelligent base stations and intelligent, remote handset terminals, each having a predetermined radio cell coverage area, and more particularly to a digital, radio cell, radio-telephone, personal communications system (or PCS) having a full ISDN interface, thereby facilitating direct interconnection and switching of PCS call traffic through the ISDN interface and the public switched telephone network, or any switched network, the personal communications system having voice/data/image (or any combination thereof) and two-way full-duplex incoming and outgoing calling capability, and being fully operational and compatible with any modulation approach selected, with the intercell protocol hand-off being provided through distributed logic which is implemented in software that is resident in the intelligent, remote handset terminals, the intelligent base stations, and the public switched telephone network (or any switched network) equipped with a PCS service control data base.

While specific embodiments of the invention have been shown and described, it is to be understood that numerous changes and modifications may be made therein without departing from the scope, spirit and intent of the invention as set forth in the appended claims.