Method of call routing to a cordless telephone service subscriber.

A method of routing a call to a wireless telephone subscriber

The invention relates to a method for forwarding a call to a subscriber of a wireless telephone service. Such a network has a number of fixed stations that allow subscribers to establish telephone connections to the public network of choice with portable telephones that are connected to the fixed stations by radio. The range of the stations is short 10 and calls are not automatically transferred from one station to another.

To establish a connection, the subscriber must come close to a fixed station, within a radius of the order of 100 or 200 m, whereas the subscriber cannot receive 15 calls. In known networks, the call cannot be forwarded to the subscriber because there is no known method for inferring which station is in the vicinity of a particular subscriber at a given moment. To remedy this drawback, it is known to connect to a conventional cordless telephone 20 a paging receiver with an alphanumeric display which allows the subscriber to be informed of the telephone number to which the subscriber must call in order to make the desired call. The disadvantage of this method is that it is impractical for the calling subscriber and that, on the other hand, it is more expensive because it uses two telecommunication networks: a radio paging network and a wireless telephone network.

The first object of the invention is to provide a method in which no radio paging network is used and in which the subscriber 30 does not have to establish a connection himself in order to forward the call to this subscriber in the event that there is a fixed station near the subscriber. Another object of the invention is to provide a method by which a subscriber can move within a known and several other fixed stations within this zone without having to worry about reporting transitions within this area. A third object of the invention is to provide a method by which a subscriber can move to another zone which is not known in advance, while maintaining the possibility of receiving telephone calls if the subscriber takes care of announcing his presence in this zone by a simple procedure. A fourth object of the invention is to provide a method by which a subscriber who has temporarily moved to a zone that is not known in advance can limit the time at which calls are forwarded to that other zone so that calls are then automatically forwarded to the station normally closest to the subscriber, and further to other stations covering a previously known zone in which the subscriber resides occasionally. A fifth object of the invention is to provide a method by which a wireless telephone network operator can automatically limit the length of time calls are forwarded to a zone other than the one in which the subscriber normally resides, in order to avoid systematic routing of calls to a zone where the subscriber never responds. left that zone and failed to carry out the procedure, which allows the network to know the location of the subscriber.

More particularly, the invention relates to a wireless telephone25 service implemented using a smart grid, which will be explained later.

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A method for forwarding a call to a subscriber to a wireless telephone service implemented over a network comprising:

- a distribution network with fixed stations and cordless digital telephones connected by radio to fixed stations,

- a universal selective digital multiservice network to which each fixed station is specifically connected by a signaling channel between users,

- network service control centers connected to an optional network, each with a wireless telephone subscriber database and logical equipment for handling calls,

- according to the invention, the service management center with a reference database is characterized in that it includes for each subscriber entitled to receive the calls forwarded to himself:

- assigning a public network numbering plan number to 15 subscribers,

- assigning a number, called the nearest station number, which indicates the station assumed to be closest to the subscriber,

- entering the number of the nearest station in the database of the network service control center serving this subscriber, including the numbering plan number and the word identifying the subscriber's telephone, and that the method includes, for each call forwarded to the subscriber:

- reading the number of the nearest station and the word identifying the subscriber's telephone from the database of the control center of the network service serving that subscriber,

- sending this word from the network service control center to the station indicated by the nearest station number via the signaling channel between the users of this station and then disconnecting this connection,

- sending at least one paging message containing said word and station number from the station,

- receiving an invitation message on the subscriber's telephone, identifying the identifying word of the telephone and alerting the subscriber,

- establishing a connection between the subscriber and said station by sending a reply message from the subscriber's telephone to the station, containing the word identifying the telephone and the station number.

The method thus defined allows the call to be forwarded automatically to the subscriber because the nearest station of this subscriber is predetermined and the number indicating this station is written in the database of the network service control center and the numbering plan number and the subscriber's phone identification word are appended to the number. This allows the station number to be obtained by using 20 subscriber numbers in the numbering plan as a key. The connection between this station and the subscriber can be established without ambiguity in the identity of the answering telephone and the station receiving this response, since the station sends an invitation message containing: a telephone identification word corresponding to a single telephone and a station identification number. Only the phone that responds to this word responds, and only the station indicated by the station number in the phone's response message responds to this response.

In another aspect, the method further comprises assigning at least one second number, called an extension number, indicating a station that may be suspected of being near said subscriber when the subscriber is not closest to the presumed station and then storing it in a database of the network service control center serving said subscriber, if such an additional status exists, and if the called subscriber does not respond to the paging messages sent by the station indicated by the nearest station number, the method further includes:

- reading the number of each additional station from the database of the control center of said network service,

- sending a word identifying the subscriber's telephone from said network service control center to each additional station via a signaling channel between users connecting the station to the network,

- sending at least one paging message containing the word identifying the telephone and the number of the station transmitting the message in parallel from each additional station.

The method thus defined allows a subscriber to move within a zone covered by multiple stations without having to perform any procedure to notify the network of a move within that zone, since the number of the nearest station and the numbers of additional stations are predetermined and stored in memory.

In another aspect, the method for determining the number of the nearest station and the number of at least one additional station comprises that the wireless telephone network operator assigns an agreed nearest station number and at least one agreed additional station number when the subscriber signs his subscription.

With the method thus defined, the number of the station near which the subscriber is normally located, as well as the numbers of the 35 additional stations to which the subscriber can randomly move, can be determined in a very simple manner but difficult to change. Agreed sub-stations are usually stations close to the nearest nearest station, but this is not necessary. The subscriber may indicate that he is normally close to the station serving his place of work and that he is outside working hours close to the station serving his place of residence5, which may be at an arbitrary distance from the workplace. The operator can easily determine the station numbers either by looking at the station layout chart or by using a table that lists all stations by geographic areas.

According to another feature, the method includes determining the number of the nearest station and the number of at least one additional station, if such an additional station exists, after the subscriber moves to a zone unknown in advance and covered by one or more stations:

- sending a message requesting the assignment of a temporary nearest station number and at least one temporary additional station number, if any, to the subscriber's telephone to the network service control center serving that subscriber via a station close to the subscriber,

- appending a number indicating that station to message 25 as it passes through the station,

- verifying the identity of the telephone that sent the message,

- entering the number of said station in the database of the network service control center, combining the numbering plan number and the identifying word of the telephone to form the temporary nearest station number,

- assigning at least one number indicating a station close to the station indicated by the temporary nearest station number by reading Table 102439 of the Network Service Control Center,

- entering each number read from the table in the database of the network service control center by appending to the number the numbering plan number and the unique word of the telephone, each number read forming the number of the temporary extension,

the expiry date of the provisional numbers, and

-predicting the time in advance and then writing them to the database of the network service control center, including the numbering plan number and the unique word of the telephone, that the method includes the number for reading the nearest station:

- reading the agreed nearest station number and the temporary nearest station number and reading the expiry date and time, ·; ·; 20, · - if the expiry date and time have not expired^: the nearest nearest station number shall be taken as the nearest nearest station number, otherwise the agreed number, and that the method for reading the number of each additional station shall include:

• · • · · • · ·

- reading the agreed extension number and temporary extension number and reading the expiry date and • · • ”30 time, • · • ₉ • · · · “*. - if the expiry date and time have not been exceeded • * *: each temporary extension number is taken as the extension number, otherwise each agreed extension number.

The method thus defined allows the subscriber's temporary 102439 to move to a previously unknown zone served by one or more stations other than those defined in the subscriber contract, by performing a location procedure that allows the temporary nearest station number and possibly one or more additional temporary station numbers to be determined. Assigning additional stations is performed automatically by reading from the table, with temporary additional stations always being the stations closest to the temporary nearest station. The subscriber cannot influence their choice.

Setting an expiration date and time for temporary numbers allows the nearest station number and extension numbers to be automatically reset to 15 agreed Numbers without the subscriber or network operator having to take action when the subscriber returns to their normal zone.

The subscriber can thus return to his normal zone without having to consider performing any special procedure to provide information to the network. The network operator, in turn, has the certainty that this will prevent poor network utilization due to unnecessary routing of calls to a zone where the subscriber is not present because the subscriber has returned to his normal zone.

There are two options for determining the validity period in advance.

According to the first variant, the method includes:

- setting a deadline using the dial pad on the subscriber's telephone after requesting the assignment of temporary station numbers,

- sending this deadline from the subscriber's telephone to the network service control center.

the expiry date of the provisional numbers, and

-calculation of time based on time.

Using the method thus defined, the subscriber can, in the same message, request the network to temporarily locate it and determine the validity period of the temporary station numbers. This makes it possible to take advantage of the fact that the subscriber usually knows after what time he will return to his usual zone. The network service control center determines the date and time corresponding to the end of this period and then enters them in its database, including the numbering plan number and the subscriber identification word, so that when the call is forwarded, the network service control center reads simultaneously: agreed numbers, temporary numbers, expiration dates and expiration dates. which is available by numbering the numbering plan. The online service control center compares the expiration date and time with the date and time the call must be forwarded. If the expiration date and time have not been exceeded, the network control center will use temporary station numbers, otherwise it will use the agreed station numbers.

According to another variation, the method includes temporary::; 25 to determine in advance the expiry date and time of station numbers:

• · • · · • · · • ·

- setting a uniform validity period for all • · · subscriber subscriptions, • * - 30 • · * ^:... · '- the expiry date of the temporary station numbers. calculating the time and time for each subscriber subscription • · ·,; on the basis of this uniform time limit and the moment at which the temporary numbers are assigned to the subscriber line35.

These two variations can be used simultaneously to determine the default time in case the subscriber forgets or does not want to set the time himself. If the subscriber requests the assignment of temporary station numbers but does not enter the expiration time with his dial pad, the network5 service control center automatically determines the expiration date and time based on a uniform deadline set by the operator and writes them to its database.

The invention will be better understood and other details thereof will become apparent from the following description and the accompanying drawings, in which:

Fig. 1 shows a general diagram of an embodiment of a wireless telephone network with an intelligent network structure enabling the use of the method according to the invention, Fig. 2 schematically shows several zones served by 20 different station groups, Fig. 3 shows a time diagram comprising assigning the subscriber's temporary25 number to its nearest station,

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Fig. 4 is a timing diagram illustrating an embodiment of a method according to the invention for forwarding a call to a subscriber located near the station indicated by the nearest station number; Fig. 5 is a timing diagram illustrating an embodiment of a method according to the invention for forwarding a call to a subscriber located near a station.

Figure 1 shows, by way of example, a general diagram of an intelligent lan102439 wireless telephone network in which the method according to the invention can be used. The network includes: distribution network

1, universal selective digital multi-service network 2, network of service control units 3 and access control units

4, 7, 8, 9.

Distribution network 1 includes portable digital cordless telephones Tl, ..., Tn and fixed stations ΒΙ,.,., Βρ. Each telephone may be connected by radio 10 to a fixed station in the vicinity of that telephone, each fixed station being able to serve several telephones simultaneously. Each station ΒΙ,.,., Βρ is connected to the public selective network 2 by means of standard interfaces 5. Each connection 15 of the network 2 includes a user signaling channel marked D and a plurality of telephone channels marked B. The number of telephone channels may be two for the basic connection and 30 for the main connection. These telephone channels are bidirectional and are circuit-switched foxes. The signaling channel between users is a two-way channel used in the message switching mode. It allows data to be sent alongside calls. One of its conventional applications is to send the telephone number or name of the calling subscriber to a display device on the telephone of the called 25 person.

Public Selective Network 2 consists of Independent Relay Centers (CAAs) and Service Interface Centers (CASs). In this example, the network includes two of these relay exchanges 10 and 11 themselves, which are connected to the two service interface centers 12 and 13 by connections in accordance with CCITT Recommendation No. 7. In this example, the stations ΒΙ,.,., Βρ are connected to an independent switching center

10.

In this example, the network 3 of service control centers includes two network service control centers (PCS-R) 14 and 15 and a service management center (PCS-G) 16. The network service control centers 14 and 15 are connected to service interface centers 12 and 13 by connections according to CCITT Recommendation 7. control center 16 with connections according to CCITT recommendation X25. Each access control unit 4, 7, 8, 9 mainly comprises a display terminal. The terminals are assigned to different access control groups, with the service management center 16 providing each group with information and the opportunity for dialogue.

Terminal 4 is addressed to the smart grid technical operator. Terminal 9 is addressed to the technical operator of all fixed stations or a specific group of fixed stations. It is an ASCII terminal or a videotext terminal. It can access the database of the service management center 16 via the station management server (SGB) and the statistics server (SDS) 19. Terminal 8 is a video text terminal that allows a subscriber to query service information: subscriber interface information and billing notifications. It can access the database of the 20 management units 16 via a user server (SAU). Terminal 7 is a videotext terminal addressed to a commercial wireless telephone service operator. The terminal can access the service management center 16 by means of a subscriber management server (SGA) 17.

Each station B1, ..., Bp has a control unit which monitors the connections: via the standard connections 5 to the network 2 and to the radio channels. The control unit performs the following tasks:

- Initiate a network call when a phone

Tl, ..., Tn reserve a radio channel,

- participation in the identification of the calling subscriber,

- analysis of data received via radio channels,

- control of radio channels.

The service request from the user of the public network 2 is analyzed in one of the service interface centers 12 or 13 and then sent to the network control center 14 or 15 serving this interface center. This network control center then controls the call handling unit and commands the service interface center for any action that requires switching means, for example to send a voice message or to establish a connection between the network input and the network output or to provide a time delay. The network service center has a program for each service, processed in a queue of initial deliveries, to process each call in a manner dependent on the messages received. It also has a real-time updated database.

The service control center 16 does not participate in the processing of calls. Instead, it forms benchmark data for the service because it contains a database of service software and subscriber information. It takes care of the technical operation control of the network of 20 service control centers 14 and 15, in particular the maintenance of database compatibility and the commercial control of operations: contract management, operator and subscriber access.

The service control centers 14 to 16 may consist, for example, of multiprocessors ALCATEL8300 marketed by ALCATEL.

The network service control centers 14 and 15 are used to perform a method for forwarding a call to a wireless telephone service subscriber. Each network control center has a subscriber database for wireless telephone service. This database contains information corresponding to all or part of the subscribers of the service. The service management center 16 updates this database seemingly simultaneously in all the databases 102439 of the network service control centers 14 and 15 when the service management center 16 has received information about the change of subscribers via the access control center 7.

The database of the web service control center 14 and 15 contains for each subscriber:

- the word IDAB, which indicates the local loop,

- the word IDCP, which identifies the telephone held by the subscriber,

- this subscriber's own secret key Ki,

- the word IDSO, which identifies the operator of the service and the service covered by the subscription,

- type of local loop: international, which authorizes all calls, national, which authorizes only one country, or limited, which authorizes a list of predefined numbers, the right to receive calls through a single station or group of stations, or through two groups of stations, one of which not known in advance

- the numbers that this subscriber can access,

- the expiry date of the local loop,

- the number of the numbering plan by which the subscriber can be called by his cordless telephone,

- the agreed number of the nearest station of the subscriber,

- the agreed numbers of the additional stations, if any, and if the subscriber has subscribed to the local loop supplement in order to be entitled to receive calls through stations other than the nearest station specified in the contract,

- temporary number of the subscriber's nearest station, if the subscriber has announced his new location and if the subscriber has subscribed to a local loop supplement to receive calls through two station groups: the first group covering the subscriber's usual oles35 and the second group covering the unknown location in advance,

- temporary additional station numbers,

- the date and time of expiry of these temporary numbers.

Figure 2 schematically shows three separate geographical zones Z1, Z2 and Z3 covered by three groups of stations. The zones Z1 are covered by stations B1, B2, B3. Zone Z2 is covered by stations B4, B5, B6. Zone Z3 is covered by one station B7.

When a subscriber signs his subscription to a wireless telephone service requesting the right to forward calls to himself, the subscriber informs the commercial operator of the wireless telephone network of his normal place of residence. For example, a commercial operator may have this subscriber normally located in the vicinity of station B1.

The subscriber indicates the extent to which he is moving. Using the diagram or the zone-by-zone table listing the stations, the operator concludes that the subscriber moves in zone Z1, which is covered by station B1 and stations B2 and B3. For example, a subscriber may work in an airport building but knows that he occasionally visits two other buildings in that airport.

In this example, the operator writes to the subscriber the number of the nearest station agreed with the database of the network service control center 14, which is the number of station B1, and the two numbers of the additional station, which are the numbers of stations B2 and B3.

This information enables the call to be forwarded in the network service control center 14 to this subscriber so that the connection to the telephone T1 of this subscriber is connected primarily by means of the station B1. Station B1 then sends an invitation to this subscriber's telephone T1. If the station B1 does not receive a response from the telephone T1, the network service control center 14 tries to establish a connection with the stations B2 and B3 simultaneously so that the calling subscriber does not have to wait too long.

Assume that a subscriber has subscribed to a subscriber subscription supplement in order to obtain the right to receive calls through another station group that is not known in advance. For example, the subscriber may go to zone Z2, which is in the vicinity of station B4. The subscriber uses the T10 key 10 of his telephone to give a command to perform an automatic determination of the station closest to him and the additional stations belonging to the group of stations covering the geographical zone defined by the station closest to the subscriber. In this example, station B4 receives a message sent by the wide telephone ti15 and informs the network service control center that the subscriber is in the vicinity of station B4. The network service control center 14 reads a table indicating that the station is located in the geographical zone Z2 and that this zone is covered by the stations 204, B5, B6. The network control center concludes that the stations

B5 and B6 are neighboring stations that can be used in addition to forward calls to the subscriber when the subscriber's response has not been followed by the forwarding performed by station B4.

The number for station B4 forms the number of the temporary nearest station, while the numbers for stations B5 and B6 form the numbers of the additional stations. These temporary numbers are used instead of the agreed numbers for a certain period of time. Their number may be greater or less than the number of agreed numbers. Agreed numbers are not deleted from the online service control center database when assigning and writing temporary numbers to the database.

In this embodiment, the validity period of the temporary numbers is limited by two time limits. The subscriber may il102439 complain to the network service control center 14 about the validity period. Otherwise, the network operator shall set a different deadline, for example one day, which shall be the same for all subscribers and which shall limit all subscribers who have not notified the deadline,. the period of validity of the temporary numbers. With this equal time limit set by the operator, it is possible to avoid calls reserving network capacity when they cannot lead to a result because the called subscriber 10 has left the zone where the subscriber has been temporarily present.

The expiration date and time are written to the network service control center database each time a new group of 15 temporary station numbers is written to the subscriber interface information. The network service control center 14 calculates the expiration date and time as a function of the date and time when the temporary station numbers are assigned and either as a function of the time specified by the subscriber's dial pad or, in the absence of a time specified by the subscriber, as a function of the operator.

In the event that a subscriber enters zone Z3, which is served by a single station B7, the determination of the nearest station finds the nearest station B7 and the determination of additional stations states that there are no additional stations. An agreed identifier is entered in the database as a temporary extension number, indicating the absence of extension stations. The expiration date and time are determined in the same way as in the case of additional stations.

Fig. 3 is a time diagram showing data exchange during the temporary nearest station number determination procedure. Time progresses from top to bottom in the figure. Initially, the subscriber unlocks his phone by entering the secret code on the dial pad. The check is performed on the phone itself. Unlocking is followed by a reservation of a radio channel to establish a connection to the station B4 near the telephone T1 according to a standard standard procedure.

The telephone T1 then sends two words IDCP and ICSO to station B4. The word IDSO identifies the wireless telephone service and its operator. The word IDCP identifies the phone Tl. Station B4 checks that the word IDSO means a known 10 operator and then sends a message to the telephone T1 indicating that the requested service is available.

Station B4 simultaneously sends to the independent exchange 10, in accordance with Recommendation No. 7, a message marked EXECUTE, which contains a field specially reserved for inter-user signaling. This field contains: the code word indicating the requested service, i.e. the wireless telephone service, the words IDCP and

IDSO, and the word BSN, which is the unique number of station B4.

The independent relay center 10 sends a message IAM containing the same words to the service interface center 12.

The latter sends to the network service control center 14 a message containing the same words, which is marked 25 ISSUE COMMANDS.

The network service control center 14 then generates a random number marked RAND and sends it to the service interface center 12 in a message marked DEVELOP SIGNAL in the field reserved for user signaling. The service interface center 12 sends to the independent relay center 10 a message marked ACM and containing the random number RAND. The independent relay center 10 forwards the random number RAND to station B4 35 in a message marked ALARM. Station B4 forwards the random number RAND to the telephone T1, which uses it to calculate the symbol SREF as a function of the secret key Ki stored in the telephone T1 and which is the subscriber's own. The ID is calculated using a conventional encryption algorithm.

The key Ki is included in the burglar-proof module, which is si-. placed in the telephone T1 and which makes the telephone personal to a particular subscriber. This module further includes the word IDAB, which identifies the subscriber interface independently of the word IDCP, which identifies the telephone T1 in which the module is located. The telephone T1 sends to the station B4 the word SRES containing the identifier and the word IDAB. Station

B4 then sends a tone to the telephone T1 prompting the calling subscriber to enter the called number.

Station B4 sends the words SRES and IDAB to the independent relay center 10 in a message marked IUU. The independent relay center 10 forwards them to the service access center 12 in a message marked OTHER. The service interface center 12 forwards them to the network20 service control center 14 in a message marked CASE.

The subscriber enters a number on his keypad. In this case, the number indicates the location service. This localization service is performed by the network service control center and * determines the number of the temporary nearest station and the number of one or more temporary additional stations, if neighboring stations • »! J, · exist. The service number is followed by two numbers that • · ·:: r indicate the expiration time of the temporary station numbers. '30 time, i.e. the time at which the • I · subscriber leaves this zone. If the length of the subscriber's stay exceeds one day, the subscriber shall also notify • · ·!₍ J expiration date.

«*« »I • ·

Station B4 implements the usual timings between subscriber number numbers. The calling subscriber terminates the assignment of the number with a dial termination signal which touches the transmission of the called number from station B4 to the independent exchange 10 in a message marked IUU. The independent switching center 10 forwards the called number to the service switching center 12 in a message marked

OTHER. The service interface center 12 forwards the called number to the network service control center 14 in a message marked CASE.

The network service control center 14 verifies the identity of the calling subscriber 10 and checks whether the subscriber is authorized to access the called number. The network service control center 14 generates a reference code denoted by SRES-OK, a random number RAND and a secret key Ki corresponding to the subscriber indicated by the word IDAB, which key is read from the network control center database. The algorithm used is the same as that used in the T1 phone. It depends on the service provider. It is known from the word IDSO sent by the telephone T1.

The web service control center 14 performs several checks. It checks that the SRES identifier is the same as the SRES-OK reference identifier to detect potential abusers who may use the subscriber's words IDAB and IDCP after intercepting them. It checks that the word IDAB, which identifies the subscriber interface, corresponds to the valid subscriber interface. It checks that the IDAB corresponds to the unique ID ID of the telephone T1.

The network service control center 14 further verifies that the subscriber has signed the call forwarding service intended for him. If any of the checks are negative, locating the subscriber will be blocked. An acoustic signal or voice message informs the subscriber of the blocking, after which the network service control center 14 disconnects.

If all checks are positive, the network service control center 14 writes to its database station B4 nu102439 as the temporary subscriber's nearest station number.

The network control center then determines the temporary numbers of the additional stations B5, B6 by reading from the table in its database the numbers of the stations belonging to the same zone Z2 as the station B4. The network control center then writes the numbers of these stations B5, B6 in its database as temporary numbers of the additional stations. It then determines and writes in its database the expiration date and time10 for these temporary station numbers.

If the subscriber has indicated the expiry time after providing the number requesting access to the localization service, the date shall be the date on which the localization is performed and the time shall be the time indicated by the subscriber. If the expiration date has not been specified by the subscriber, the network service control center 14 calculates the date and time as a function of the date and time of the localization performed and the expiration date set by the operator for all subscribers. The date and time thus determined are written to the database.

The network service control center 14 sends a CREATE / CONNECT message to the service interface 25, which contains a message indicating that the localization of the subscriber has been completed. This message is forwarded to the subscriber's telephone T1 via the previously established connection. The telephone T1 then disconnects the connection and the disconnection 30 initiates the generation of a charge notification at the network service control center 14. The network is then ready to route calls to the subscriber, at the same time as the subscriber is in zone Z2, which is different from the zone in which the subscriber normally is.

Fig. 4 is a timing chart illustrating the exchange of information in a call to a subscriber in the case where this subscriber is in his usual zone Z1 near station B1, which is the usual station closest to the subscriber. There is no valid temporary number. The network service control center 14 thus forwards each of its calls via station B1 and, secondarily, via stations B2, B3 indicated by agreed numbers.

Time progresses from top to bottom in the figure. The calling subscriber initiates the call by sending, by means of a telephone terminal, a message marked SETUP to an independent switching center serving this subscriber, for example independent switching center 10. This message contains a codeword indicating the wireless telephone service and a called number indicating the subscriber's public telephone network 15 numbering plan. . The independent relay center 10 sends this information to the service interface center 12 in a message marked IAM. The service interface center 12 forwards this information to the network service control center 14 in a message marked GIVE COMMAND. The network service control center 14 issues a command to send a wait message, the purpose of which is to make the calling subscriber wait, by sending a message marked CREATE / CONNECT to the service interface center 12.

On the other hand, the network control center searches its database for the information used to transmit this call: the agreed nearest station number, the agreed extension numbers, the temporary nearest station number, the extension numbers, the expiry date of these temporary numbers and

timed. It infers the station numbers to be used to forward this call: STATION N: 0 1, STATION No. 2, STATION N: 0 3, which represent stations B1, B2, B3, in the example where there are no valid temporary numbers.

On the other hand, the word IDCP is obtained from the database, which indicates a telephone T1 corresponding to the numbering plan number sent by the calling subscriber. This word IDCP is used in place of the numbering plan number to connect across the network. The network service control center 14 sends the word IDCP and the number of the nearest station STATION NO

1 to the service interface center 12 in a message marked CREATE / CONNECT. The service interface center 12 forwards this information to the independent relay center 10 in a message marked EXECUTE. The independent relay center 10 forwards the word IDCP to the station B1 in a message marked CALL RECEIVED.

Station B1 then issues a command to disconnect the connection with a disconnection message transmitted by the independent relay center 10 and the service interface center 12 to the control center 14. Station B1 sends a paging message to the telephone T1, this paging message containing the word IDCP and the station number STATION N: 0 1

The telephone T1 waits, sequentially examining the 40 radio channels used for the connections between the telephones and the stations, until the telephone detects a paging message containing the word IDCP indicating this telephone. Upon detecting such a message, the telephone reserves the same radio channel that transmitted the paging message, with each channel being used alternately in both directions. The telephone sends a response message including: an identifier indicating the response to the call, the word IDCP indicating the telephone T1, and the number STATION N: 0 1 indicating the station B1. Station B1 receives this response message and identifies its 30 station numbers.

Neighboring stations may also receive this response message, but they do not recognize their station number and therefore do not interfere with station B1 as it tries to establish a connection. Station B1 checks that the responding telephone sends the same word IDCP as that sent in the paging message to avoid confusion if several telephones send reply messages at the same time. Station B1 then sends to the independent exchange 10 a message labeled SETUP containing a codeword indicating the wireless voice service to establish a connection as well as a subscription.

in the case of an invitation issued on the initiative of the The independent relay center 10 sends a message IAM to the service interface center 12, which contains a codeword indicating the service. The service interface center 12 sends a message marked GIVE COMMANDS and containing a code word indicating the service to the network service control center 14. The latter remotely controls the establishment of the connection by sending to the service access center 12 a message marked CREATE / CONNECT and containing the word IDCP indicating the telephone T1.

A little later, when the data transfer is completed, the holder of the telephone T1 subscription initiates the disconnection. The telephone T1 sends a message giving a command to disconnect, and the station B1 further sends a disconnect command through the independent relay center 10 and the service interface center 12. The network service control center 14 then generates a charge notification.

Fig. 5 is a time diagram showing data exchange in the case where the telephone T1 does not give an answer to the station B1 because the subscriber has moved in the zone Z1 and is in the vicinity of the station B3. The diagram is similar to that in Fig. 4 until the connection established for sending the paging message between the network service control center 14 and the station B1 is disconnected. In the absence of a response from the subscriber, the network service control center 14 waits for a time predetermined delay by the scheduling program, after which it connects simultaneously to stations B2 and B3, which are indicated by the station numbers STATION N: 0 2 and STATION N: 0 3.

Stations B2 and B3 are controlled in a manner similar to that described in connection with station B1 so that they send paging messages containing the word IDCP and the stations' own numbers.

STATION No. 2 and STATION No. 3, respectively. In this example, the telephone T1 does not receive the paging message 5 transmitted by station B2. Instead, it receives the paging message sent by station B3, and this initiates the sending of a response message, which also contains together the word IDCP identifying the telephone T1 and the station number that sent the paging message STATION No. 3. Station B3 receives this response message 10 and verifies that it is indeed the intended response and that the responding telephone corresponds to the transmitted word IDCP. If these checks are positive, station B3 requests a connection as previously described in connection with Figure 4. The connection is also disconnected in the same way.

Next, let us consider the case where the subscriber is outside his usual zone Z1. The subscriber requests the location service to determine the number of the temporary nearest 20 stations and the numbers of temporary additional stations. It is assumed that these have not yet expired. The temporary number of the nearest station is, for example, the number indicating station B4, and the temporary numbers of additional stations are numbers indicating stations B5 and B6.

The exchange of information for forwarding the call to the subscriber then corresponds to that shown above in connection with Figures 5 and 6, but the numbers STATION N: 0 1, STATION N: 0 2, STATION N 3 are then the numbers denoting stations B4, B5 and B6.