CA2068941C - Device and method for telephony interconnection intended to offer continuity of service to independent stations in a communications network - Google Patents

Abstract

Device and method for telephony interconnection intended to offer continuity of service to independent stations in a communications network.

In a communications network between fixed stations and fixed terminals, the said fixed stations being linked to the telephony channels while the fixed terminals comprise an antenna for mutual interaction over distance with independent stations, means of connection to the telephony channels of the network are provided, and there is established a telephony relationship between an independent station (SA) and another station (SF) linked to the telephony channels of the network, by the intermediary of a primary link between the independent station (SA) and the connection means, via the antennas of a primary fixed terminal (BFR1). A
secondary fixed terminal (BFR2) is chosen on the basis of predetermined selection criteria, and a secondary link is established between the independent station (SA) and the said connection means, via the antenna of the said secondary fixed terminal (BFR2). In response to a predetermined station condition, relating to the said primary link, a predetermined request information item is generated from the independent station and, in response to reception of the said request information item, the said relationship is switched so that it passes through this secondary link.
(Figure 2)

Description

Device and method for telephony interconnection intended to offer continuity of service to independent stations in a communications network.
FIEI.D OF THE lNV~;N'l'ION
The invention relates to telephony.

It is more particularly intended to serve in a c~ n;ca-tions network between fixed stations, such as telephone sets~ and fixed terminals, the said fixed stations being linked to the telephony channels of the network while the fixed tP ;n~l s comprise means forming an antenna (more simply called "antenna" in the rest of the text) for mutual interaction over distance with independent stations, such as portable telephone handsets.
PRIOR ~RT
Such a network is, for example, that ~nown by the trade-mark POINTEL, and the invention finds à particularly advantageous but not limiting application therein.

The POINTEL network does not permit, in its current definition, offering the user of a portable handset continuity of service, when the latter moves, even if all the fixed terminals situated in the vicinity of the user provi'de complete radio frequency coverage. In fact, it is anticipated currently that the telephony co~nn;cation in progress will be broken off as soon as the user moves out of the radio frequency zone covered by the fixed terminal having initialized the radio frequency link of this telephony c.- n i cation.
SUMMARY OF T~E lNv~NllON
The invention aims to provide a solution to this problem.

According to a general characteristic of the invention, the telephony device, intended to serve in a c~ n; ca-tions network of the type quoted a~ove, comprises:
- means of interface with the antennae of a plurality of fixed terminals, .. :

~ , .: :

- means of connection to the telephony channels of the network, and specific means, linked to the interface and connection means, suitable for:
establishing a telephony relationship between an independent station and another station, in principle a fixed telephony set, linked to the telephony channels of the network, by the intermediary of a primary link between the independent station and the connection means, via the antenna of a primary fixed terminal, and for establishing at least one secondary link between the independent station and the said connection means, via the antenna of a secondary fixed termin~l, chosen on the basis of predetermined selection criteria, - station-analysis means, incorporated in the independent station, suitable for generating a predetermined request information item in response to a predetermined station condition relating to the primary link.

The specific means are then, moreover, suitable for responding to th~ reception of this request informa'ion item, by switching the said telephony relationship so that it passes through this secondary link.

This secondary fixed terminal is advantageously selec-table among a chosen group of terminals which are adjacent to the primary fixed term; n~l .

According to an embodiment of the device, the inter~ace means comprise, with respectively the antennae of the primary and secondary fixed tPrm; n~l s~ first primary and se~ondary interface stages for a plurality of radio ~ 3~ frequency channels, while the specific means comprise:

.

- primary terminal-processing means, linked to the said first primary interface stage, suitable for establishing, within the said primary link, a primary radio frequency link between the independent station and the antenna on at least one of the radio frequency channels of this primary fixed terminal, for characterizing this primary radio frequency link one-two-one by a link identifier, and for delivering this link identifier to a second primary interface stage, - transfer means linked to this second primary interface stage, suitable for receiving the said link identifier and for c~ n; cating to a second secondary interface ~ stage, situated at the site of the secondary fixed t~rrin~l, a link information item containing at least this link identifier, and - secondary t~ ;n~l-procesqing means, linked to the said first and second secondary interface stages, suitable for establishing, within the said secondary linkl a secondary radio frequency link between the independent station and the antenna on at least one of the radio frequency channels of this secondary fixed terminal, with the aid of the said link identifier.

The request information item then ad~antageously contains this link identifier.

The selection criteria for the secondary fixed terminal ! can result from the analysis of at least one first characteri~tic deduced from the pri~ary radio frequency signal transmitted in the course of the primary radio frequency link on at least one of the radio frequency channels of the Drimary fixed terminal, and from analysis of at least one second characteristic deduced from this primary radio frequency signal.

-20689~1 This first characteristic is, preferably, det~rm;n~tionof the level of the said primary radio fre~uency signal in the primary fixed terminal while the second charac-teristic comprises, preferably, dete ination of the level of the radio freq-lency activiky resulting from the transmission of the primary radio frequency signal, on the radio frequency channel associated with the secondary fixed terminal, the counterpart of the radio frequency channel associated with the primary fixed terminal, on which the said primary radio frequency signal is trans-mitted.

According to one embodiment of the invention, at least part OI the constituent parts of the device can be incorporated in at least one specific module.

It is also possible for these constituent parts to be incorporated within at least some of the connecting units for the fixed terminals belonging to the c~ n;cations network.

The subject of the invention is also a method for tele-phony interconnection, intended to serve in a Cl: n;cations network of the type quoted above, in which method there is provided:

- means OI connecting to the telephony channels of the network, there is established a telephony relationship between an independant station and another s~ation linked to the telephony channels of the network, by the intermediary of a primary link between the independent station and the connecting means, via the antenna of a primary fixed 3 0 t~rm; n~ 1 ~

there is chosen a secondary fixed teL ; n~l on the basis OI predetermined selection criteria, "

,, : - . , :, ~
~

there is established a secondary link between the independent station and the said connection means, via the antenna of the said secondary fixed terminal, in response to a predetermined station condition~
relating to the said primary link, there i5 generated, from the independent station a predetermined request information item, and in response to reception of the said request information item, the said secondary relationship is switched.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages and characteristics of the invention will appear on P~;n;ng the detailed description below and the attached drawings in which:

- Figure 1 represents a block diagram of a communications network of the POINTEL type of the prior art;

- Figure 2 represents a block diagram of a first configuration of a cl- n;cations network equipped with means according to the invention;

- Figure 3 represents a block diagram of a specific modu~e belonging to the davice according to the invention;

- Figures 4, 5 and 6 diagrammatically illustrate other means of the device according to the invention; and - Figure 7 represents a second configuration of a c~ n;cations network equipped with means according to the invention.

The drawings essentially comprise elements of a speci~ic nature. That being so, they can serve not only to make the detailed description below better understood, but also to contribute, if need be, to the definition of the invention.

- :

20689~1 DESCRIPTION OF THE PREFERRED EM~ODIMENTS
It is assumed now that the invention applies to the POINTEL network whose structure provided up to the present will now be very briefly described with reference to Figure 1.

Independent stations SA, such as portable telephone handsets, are capable of mutual interaction o~er distance with a radio channel with antennae ANT of fixed radio tPrm i na 1s BFR.

The radio frequency exchanges between the independent stations and the terminals are governed by a standard of British origin called "CAI" ("Common Air Interface"). The exchanges take place by frequency modulation making use of one frequency band per radio c~ n; cation.

These fixed tPrri n~l s BFR ~are connected to terminal connecting units URB by a specialized control channel CCS. Each teL ; n~l connecting unit thus manages a group of fixed terminals BFR.

A fixed terminal can be directly connected to the tele~hony channels CTPU of the public switched telephor.e networks. In this case the unit URB which manages it is not connected to these telephony channels.

A fixed terminal may not be directly connected to the telephony channels CTPU. In this case, its connection is carried out by the intermediary of its connec~ing unit which is then directly connected to~the channels CTPU.

Each fixed ter~i n~l BFR can only send out telephone calls towards the telephony channels CTPU but can certainly send out or receive radio calls destined for or originat-ing from independent stations SA.

.

, The communications networ~ comprises, in addition to the telephony channels CTPU, a digital co n; cations medium CNPU, operating, in principle, by packets, such as -the TRANSPAC ~registered trademark) network. In the rest o~
the text, the expression "communications medium" will be replaced by the term "channel" for the sake of uniformity, although the person skilled in the art knows that the significance of the term "channel" may not be the same as in the case of telephony channels.

On to these digital signal channels CNPU are connected the various units URB as well as other constituent parts of the POINTEL network designated by the references CAP, CEPP and CEDP.

The POINTEL authorization center CAP, manages, for the whole of the POINTEL network, especially the subscriptions and thus the authorizations of the POINTEL
- users to call a fixed station SF connected to the telephony channels CTPU, from an independent station. To this end, the terminal connecting units URB are linked to the center CAP by the digital channels CNPU.

- The ~connecting units URB are also linked to the main POINTEL operation center CEPP, via the digital channels CNPU, with the aim of transfer of data relating to the telephony communications exchanged so that the center CEPP can transmit this data to a billing system.

The decentralized POINTEL operation centers CE~P are management installations intended to regionally supervise the operation of the network and especially to detect anomalies in operation of the connecting units URB and/or the fixed term;nAls BFR.

It should be noted that the centers CEDP can ct n;cater by the intermediary o~ the digital channels, data to the centers CEPP with the aim-of national supervision~

20689~1 When a telephony communication is e~changed between an independent station SA and a fixed station SF, a radio frequency link is established between this independent sta~ion and the fixed terminal BFR whose radio frequency zone covered by this fixed teL ; n~l contains this independent station. Moreover, the fixed terminal can be connected to the public switched telephone network directly, or also by the intermediary of the connecting unit URB which manages it, according to the connecting configuration of the network adopted.

As already mentioned above, when the user carrying the independent station SA goes out of the zone covered by the terminal BFR having initialized the radio frequency link, the telephony co~-ln;cation in progress is broken off.

The POINTEL network, in its current definition, as well as the CAI standard, do not -then permit offering this user the possibility that radio co~ n;cation might be automatically relayed through a tP ; n~l other than that which initialized this c~ n; cation.

The main aim of the invention is therefore to remedy this omission.

To this end, generally, there is provided:

- means of interface with the antennae of a plurality of fixed terri~s, - means of connection to the telephony channels of the network, specific means, linked to the interface and connection means, suitable g _ . - ~ ' : ' .

20689~1 for establishing a telephony relationship between an independent station and another station, for example a fixed station, linked to the telephony channels of the network, by the intermediary of a primary link between the independent station and the connection means, via the antenna of a primary fixed t~rm;n~l, for establishing at least one secondary link between the independent station and the said connection means, via the antenna of a secondary fixed ter~; n~l ~ chosen on the basis of predetermined selection criteria, and - station-analysis means, incorporated in the independent station, suitable for generating a predetermined request information item relating to the primar~ lin~;

the specific means are thus suitable for responding to the reception of the said request information item, in principle in the secondary tPrr;n~l, by switching the said telèphony relationship so that it passes through this secondary link.

In order to estahlish thP various links, the interface mean~ comprise, with respectively the antennae of the primary and secondary fixed tPr~;n~ls, ~irst primary and secondary interface stages for a plurality of radio frequency channels.
It is thus arranged that the specific means comprise:

- primary tPrr; n~l -processing mean~, linked to the said first primary interface stage of the primary fixed terminal, suitable for establishing, within the said primary link, in accordance with the CAI standard, a primary radio frequency link between the independent station and the antenna of this fixed terminal, on at least one of these radio frequency channels.

' ~ .

20689~1 The primary terminal-processing means thus characterize, in accordance with the CAI standard, this primary radio frequency link one-to-one by a link identifier LID1. This link identifier is different from the identifier LID of the POINTEL cn~m~ln; cations network which has, for example, been sent out by the independent station SA when the user has wanted to be connected to the POINTE~
network with the aim especially of calling another station. It will be seen later that, according to the 1~ invention, the request information item contains this link identifier LID1 and that the specific means will use it in order to reestablish telephone commlln;cation if the user goes out of the zone of radio coverage of the primary fixed terminal.

After having extracted this link identifier LIDl, the primary tP~rm; nal -processing means deliver it to a second primary interface stage.

The specific means also comprise transfer means, linked to this second primary interface stage, suitable for receiving this link identifier LIDl and for c~ n;cating it to a second secondary interface stage, situated at the site-~of the secondary fixed terminal. In fact, these transfer means are suitable for cl- n;cating a link information item INFL cont~;n;ng, in addition to this link identifier, other data elements which will be detailed later.

Finally, secondary tPrmin~l-processing means are provided, linked to the said first',and second secondary interface stages and suitable for establishing, within the secondary link, a secondary radio frequency link between the independent station and the antenna of this secondary fixed terminal on at lPast one of these radio frequency channels with the aid of the said link identifier LIDl.

It will ~e seen later that the first and second primary interface stages, as well as the primary terminal-processing means are advantageously incorporated in the primary fixed terminal while the first and second ~ 5 secondary interface stages as well as the secondary terminal-processing means are incoxporated in the secondary fixed terminal.

In the same way, the transfer means are preferably incorporated in the said connecting unit or units managing the primary and secondary fixed ter~i nal s .

It is possible, as will be seen later, for the primary fixed tel in~i to be connected to a primary connecting unit while the secondary fixed terminal is connected to a separate secondary connecting unit. In this case the transfer means comprise, within the primary connecting unit, primary digital interface means linked to the digital channels of the network and, within the secondary connecting unit, secondary digital interface means linked to these same digital channels. The transfer means then transmit the said link information item INFL cont~in;ng the link identifier LID1, ~etween the primary and secon-dary connecting units, by the intermediary of the digital channels and the primary and secondary digital interface means.

The primary radio frequency link comprises transmission of a primary radio frequency signal on at least one of the radio frequency channels.

The said station condition, in response to which the station-analysis means will send out the request information item (link identifier LID1), thus relates to at least one of the characteristics of this primary radio frequency signal.

~: ' In accordance with the CAI standard, the primary radio frequency signal comprises a telephony channel and a signaling channel. The telephony message, supported by the primary radio frequency signal, comprises a specific signaling part (handshake) transported by the signaling channel, as well as a part, called useful, transported by the telephony channel. The specific signaling part makes it possible to check the state of the radio link.

It is then provided that the station-analysis means analyze the presence of this specific part and carry out radio frequency transmission of the link identifier LIDl (request information item) in the absence of this specific part. This absence may result from exiting from the zone of radio coverage of the terminal or even poor radio frequency transmission quality leading to an incomprehensiDle specific part on the part of the independent station.

In addition to the means already quoted, the specific means comprise first analysis means of at least one first characteristic deduced from this primary radio frequency signal.
., This first characteristic can then consist ln determination of the level of the said primary radio frequency signal at the site of the first primary stage of the primary fixed terminal.

It is also provided that the specific means comprise second analysis means suitable for ~nalyzing, at the site of the said first secondary stage, at least one second characteristic deduced from the primary radio frequency 3Q signal. The criteria of selection of the secondary fixed t~rm; n~l can then result from analyses of the first and second analysis means.

' 20~894~
The second characteristic is, advantageously, determination of the level of the radio frequency - activity on the radio frequency channel of the said first secondary stage, the counterpart of the radio frequency channel of the first primary stage on which the said primary radio frequency signal is tr~nsmitted. This radio frequency activity then results from the transmission of this primary radio frequency signal.

In other words, the secondary ter~;n~l or other terminals lQ can perceive radio frequency activity during transmission of the primary radio frequency signal between the independent station and the primary fixed t~rmin~l.

The selection criteria for the secondary fixed terminal can also comprise, in a variant, reception of the request information item in this term;n~l.

: It will be seen later that it is possible that the transfer means will co n;cate the said link information item INFL to the secondary fixed tPrmin~l, or to all the teL ;n~ls of the group chosen from terminals adjacent to the primary fixed t~r~;n~l among which the secondary term;-n~l is selectable, before reception of the said request information item.

; It is also pos~ible, in a variant, that these transfer - means will communicate the link information item INFL to the secondary fixed terminal after reception of the request information item.

As far as the connection to the telephony channels of the network is concerned, it is provided that the connecting means comprise:

- a first interfaces block linked to the telephony channels of the network, - ' ~

2~6894~
- a second interfaces block linked to some at least of the fixed terminals of the network, and - interconnection means between these interfaces.

The specific means thus comprise specific processing means linked to these interfaces blocks as well as to the interconnection means.

These specific processing means are then suitable for:

- establishing:

1) a telephony-station link between a first interface of the first interfaces block and the said other station, in principle the fixed telephone set, 2) a primary telephony link between a first interface of the second interfaces block and a third primary interface stage of the primary fixed tPrr;n~l, and~5 3) a secondary telephony link between a second inter-face of the second interfaces block and a third secondary interface stage of the secondary fixed t~rr;n~l, - establishing the said telephony relationship by authorizing interconnection between the first interface of the first block and the first interface of the second block, then for - authorizing interconnection between the said first interface of the first block and th~ second interface of the second block in order to switch the said telephony relationship.

Having now set out the main characteristics of a general nature of the de~ice according to the invention, refer ence will now be made to Figures 2 to 6 in order to illustrate a first configuration of the cl ni cationS

20~8941 network in which at least one specific module UTP is provided, incorporating at least the first and second interfaces blocks, the interconnection means and the specific processing means.

It is provided that the device will comprise a plurality of specific models assigned respectively to separate attachment sectors. Figure 2 illustrates, for the sake of simplification, a single specific module UTP assigned to an attachment sector.

It will be assumed here that the primary fixed tPrm;nAl possesses the reference BFR1 while three fixed tPrm; n~l s adjacent to the terminal BFRl respectively possess the references BFR2, BFR3 and BFR4. The secondary fixed terminal which will be chosen is assumed here to be the terminal BFR2.

It is also assumed that in this configuration the fixed ; terminals of the network are directly connected to the telephony channels CTPU and that a primary connectin~
unit URB1 manages the fixed terminal BFR1 and BFR3 via the respective specialized links CCS1 and CCS3 while a secondary term;n~l connecting unit URB2 manages the fixed term; n~l s BFR2 and BFR4 via respective specialized links CCS2 and CCS4.

The first and second interfaces bloc~s, connected to the . 25 telephony channels CTPU of the network, comprise a ~ plurality of digitising cards for the telephony signals, bearing the reference as MIC4, ...~. MICll. These cards are, for example, those marketed by the French company AETA under reference ES0290.

The interconnection means are here represented by two digital linking buses BMIC3 and BMIC4 between the various cards MICj.

-,' " '~' ...
. ~
' Each bus BMICj has a capacity of two megabits per second.

A card SIGM analyzes the telephone numbers received from the telephony channels CTPU at the start of Cl_ n; cation. The person skilled in the art knows how to produce such a card, for example using decoders (of telephone numbers coded according to the CCITT Q-23 standard) such as those marketed by the Brit~sh company PLESSEY under reference MVa870DP.

A digital interfaces block JONM is also provided, linked to the digital channels CNPU. This interfaces block here comprises, for example, a card such as that marketed by the company MOTOROLA under reference NVME333. It is thus possible to produce a digital interface conforming to the international standard CCITT X25.

The specific processing means UCM are linked to the block J~NM, to the card SIGM and to the cards MICj by a linking bus BUCM. Physically, the latter can be produced by the card marketed by the MOTOROLA company under reference MVME 117A, based on the MOTOROLA 68010 processor incorporating the software part of these processing meansU~ with which a dynamic random access memory of 2 megabytes is associated.

Each bus BMICj is suitable for transporting digital data formed into a,frame subdivided into a pl~rality of time intervals, typically 32, referenced IT0.. IT31. The first time interval ITO and the seventeenth time interval IT16 are signaling intervals while the ,other time intervals ' are used for the various telephony channels.

- While the signaling interval ITO is used for the purposes of synchronization, the sign~ling interval IT16 is used to attribute a telephone line relating to a call ent~ring or leaving the module UTP.

, .

Thus, the specific processing means are suitable for acting on this signaling interval ITl6 in order to permit reception or transmission of a telephone call in or from the first and second interface blocks MICj.

The module UTP finally comprises supply means ALSM and ALCM capable of providing voltages of + 5 volts from the voltage of 48 volts delivered by the switched telephone network CTPU.

Figure 4 diagrammatically illustrates the bloc~ diagram of a terri n~l connecting unit URB-i. The suffix i will be assigned the value 1 when the primary connecting unit URB1 is concerned, and the value 2 when the secondary connecting unit URB2 is concerned.

The term; n~l connecting unit URB-i comprises a signaling unit URBS-i and a switching unit URBC-i as well as power supply means for these two units~ not shown here t for reasons of simplification.

The signaling unit URBS-i here incorporates transfer means while the switching unit URBC-i is not used in this variant and will be described in more detail later.

The transfer means comprise digital interface means JON-i linked to the digital channels of the network as well as to the switching unit URBC-i, and which can be produced in a manner similar to the digital intPrfaces bloc~ JONM of the module UTP.

These transfer means also comprise a plurality of inter-face cards CMBl-i...CMB4-i producing a signaling interface with the fixed ter~; n~l s BFR. These cards CMB-i can be, for example, those produced from cards marketed by the United States company FORCE COMPUTER INC. under reference SYS68K/ISIO-1/IA, associated with traditional modems.

, , 20689~1 With these various digital interfaces is associated a signaling processing unit UCS-i linked to the cards JON-i and CMB-i by a linking bus BUCS-i. The signaling processing unit is produced, for example in a way similar to the specific processing means UCM, based on the MOTOROLA processor 68010 which incorporates the software part of the transrer means.

Figures 5 and 6 illustrate a block diagram of the com-position of a ~ixed term; n~l BFR-i.

The structures of the fixed te ; n~l s BFR o~ the network are similar. Also, the various constituent parts of this fixed ter~; n~l have references allocated the suffix j.
This suffix j takes the value l when a so-called "primary" element is concerned, that is to say associated with the primary fixed terminal, and the value 2 when a so-called "secondary" element is concerned, allocated to the secondary terminal.

In the rest o~ the text, the adjectives primary and secondary may sometimes be suppressed and understood, for reasons of simplification.

The primary and secondary fixed terminals BFRl and ~FR2 respectively incorporate the primary and secondary terminal-processing means, the first primary and secondary interface stages ETl-l and ETl-2, the second primary and secondary interfaces stages MOD-l and MOD-2 as well as the third primary and secondary interfaces stages IRC-l and IRC-2.

The fixed term; n~l BFR-j comprises a power supply block ALIM-j delivering the voltages plus and minus 5 volts from an input voltage of 220 volts AC. A ter~; n~l -processing unit UCB-j is also provided, which can be produced in any way similar to the signaling processing unitO
.

.

2~68941 The second interface stage MOD-; is, for e~ample, produced Erom a card similar to that used for the cards CMB-j. This card makes possible the signaling link interface with the corresponding term;n~l connecting unit URB-j.

A radio frequency module RF-j is linked to a third interface stage IRC-j as well as to the terminal-processing unit UCB-j and to the antenna ANT-j of the terminal BFR-j.

The card IRC-j comprises a module for digital interface with the module RF-j, followed by a digitallanalog and analog/digital converter block produced, for example, on the basis of components such as those marketed by the company SGS-THOMSON under reference ETC 5067. This converter block is itself followed by a model for analog subscriber line interface with the channels CTPU in accordanc~ with the specifications for connection to the switched telephone network.

Finally, a link bus BUC-j makes it possible to link the various components of this network together.
~, As illustrated in Figure 6, the module RF-j comprises a - frequency changer stage FT-j linked to the antenna ANT-j, followed by a signal demodulation circuit ~MD-j then by a signal decoder circuit DCD-j.

This decoder DCD-j is suitable for discriminating on the one hand the signaling signals cl~ n; cated by a link SIGN-j to a processing block MPT-j, and word signals c~mnnicated by another link PAR-j to a block PHO-j forming the interface with the card IRC-j.

The processing block ~PT-j is linked to the terminal-processing unit UCB-j as well as to a synthesizer SYN-~connected, moreover, to the frequency changer stage FT-j 2~6~94~

for selection of the radio frequency channel on which the radio frequency link is established.

Such a module RF-j is, for example, that currently available from the Applicant under reference DTRF GPT-FT equipment.

It can ~e considered, functionally, that the firstinterface stage ET1-j encompasses the two frequency changer stages, the demodulation and decoding ci~cuits for the signals as well as the synthesizer.

The term;n~l-processing means as well as the first and second analysis means comprise software modules incor-porated within the blocks UCB-j and MPT-j.

We will now consider the case of a telephony co~ n;ca-tion established from the independent station SA with the fixed station SF.

When the user is connected to the POINTEL network, by using the keypad of his handset, the station-analysis means cl n; cate, for the attention of the fixed term nal BFRl, which here will be assumed to be the primary fixed terminal, the identifier LID of the POINTEL
network, as well as the identi~ier PID of the portable handset. The telephone call coming from the portable handset SA can be taken into account by the fixed ter-minal BFR1 since the primary terminal-processing means of the latter already know the identifier LID of the POINTEL
network. The telephone number of th~ called station, also composed on the keypad of the handset, as well as the identifier PID of this portable handset are transmitted by the intermediary of the primary connecting unit URBl and digital channels of the network to the POINTEL
authori2ation centPr CAP for checking.

, 2~8941 When this checking is carried out, the transfer means of the primary connecting unit URBl establish a digital link with the specific module UTP by the intermediary of the digital channels of the network. This digital link has the aim of requesting ~rom the specific processing means of the module UTP a call number of this specific module UTP by the intermediary of the switched telephone network CTPU. This telephony call number is referenced ABPQMCDU.

This call number ABPQMCDU is associated one-to-one with the identifier PID of the independent station and is cn~ ln; cated to the connecting unit URBl, returning via the diqital channels of the network.

The transfer means of the unit URBl then comm~ln;cate via the signaling line of the specialized link CCSl the call number ABPQMCDU as well as the authorization from the POINTEL authorization center CAP, to the primary terminal-processing means of the tPrmi n~l BFRl.

The primary radio frequency link is thus maintained between the portable handset SA and this fix~d terminal and is characterized as quoted above by the link identifier LIDl, associated one-tO-Qne with this link, and differing from the network identifier LID.

The primary terminal-processing means then cr ni cate to the connecting unit URBl this link identifier LIDl.
The transfer means of this connecting unit then broad-cast, by the intermediary of these digital channels of the network and the specialized .links to all the terminals BFR2, BFR3, BFR4 adjacent to the t~rmin~l BFRl, the link identifier INFL, containing the identifier LIDl, as well as the call number ABPQMCDU of the specific module and the identifier of the independent handset PID.

Let us now return to the establishment of the primary link between the termin~l BFRl and the fixed station SF.

:.

, 20689~
The primary terminal-processing means call the specific module UTP by the intermediary of the switched telephone network CTPU, with the aid of the call number A~PQMCDU.
In fact, only the MCDU part of this call number i5 analyzed and used by the module UTP.

This "half-call" from the fixed terminal BFRl to the specific module is received in the first interface of the second interfaces block of this module and will con-tribute to the establishment of the said primary telephony link.

The specific processing means of the mcdule UTP then allocate, by the intermediary of the bus BMIC-j, the first interface of the first interfaces block so as to reserve a telephony line for the second "hal~-call" from the specific module UTP to the station SF, which will contribute to the establishment of the said telephony-station link.

When this allocation is carried out, the switched tele-phone network sends, by the intermediary of the specific processing means of the module UTP, a call tone to the primary term; n~l -processing means of the terminal BFRl, and bring about interconnection between the first interfaces of the first and second interfaces blocks of the connection means.

The primary terminal-processing means then dial the telephone number of the called station SF which will have the consequence of putting the station SA in co -~;cation with this station SF.

In the course of the telephony c~ n; cation~ when, for example, the user moves and exits the zone of radio coverage o~ the term; n~l BFRl, or else if there is any radio interference, the station-processing means of the handset will detect the lowering in level of the primary ~068941 radio frequency signal, especially when the latter no longer receives the specific part of the telephony message (thus the said predetermined station condition is present here).

In this case, the station-processing means will broadcast, on the various radio channels, the request information item, that is to say the link identifier LIDl.

All the fixed tPrmi n~l S BFR2, BFR3 and BFR4, adjacent to the terminal BFR1, are able to recogni~e the link identifier LIDl since their respective terminal-processing means have had foreknowledge of it.

It will be assumed, now that the user has approached terminal BFR2, that it is this latter terminal which receives the identifier LIDl and which is therefore chosen among the group of adjacent te i n~l S to be the secondary fixed tPrr; n~l, On reception of this link identifier ~IDl, the secondary tPrm;n~l-processing means of the secondary fixed terminal are s~itable for sending a secondary call signal to the said second interface of the second block, with the aid of the call number ABPQMCDU of the specific module, which will contribute to the establishment of the said secondary telephony link. In practice, only the part MCDU
of this call number is transmitted by the switched telephone network CTPU to the module UTP.

On reception of this secondary call signal at the second interface of the second interfaces block of th~ specific module UTP, the specific processing means cause the interconnection between the first interface of the first interfaces block and this second interface. The telephony relationship between the independent station SA and the fixed station SF is thus switched and the user is offered .

2~89~1 continuity of service.

In order to prevent untimely switching between two primary terminals, and in order to possibly leave time for the primary ~ixed terminal BFRl to pick up an interrupted radio frequency link again, especially in the case where an independent handset finds itself equidistant from two fixed termin~ls, it is preferable for the secondary terminal-processing means of the secondary fixed tR i n~l BFR~ only to transmit the said secondary call signal after a predetermined time delay typically of the order of 3 seconds, starting on first reception of the said link identifier LID1 at the said first secondary stage of this secondary fixed terminal BFR2. It will be recalled, in fact, that the station-processing means are able to send out the link identifierat regular intervals until the latter is received by one of the fixed ~eL inAls.

We will now consider the case where the fixed station SF
wishes to establish telephony cl nication with the independent station SA.

In order that the independent handset SA can be called, at no matter what geographical location, it is appropri-ate that it can be located with re pect to a chosen fixed terminal. This location information i5 stored in means forming a data base BDP a~sociated with each specific module UTP and contained, for P~mple~ in the 2 megabytes dynamic-random-access memory of the MOTORO~A 68010 processor. This data base BDP comp~ises, in addition to the location information of the chosen fixed terminal, here terminal BFRl, and therefore of the independent station SA, the correspondence between the call number of this handset SA and its physical identifier PID.

This location information results from a locating dialogue between the independent handset SA and the - 20~89~
chosen terminal BFR1.

The Applicant currently prefers to contemplate the principle of voluntary location on behalf of a subscribe~
wishing to receive tele.phone calls on his independent handset. It is assumed that this is the case here for the user carrying this independent station SA. This wish is recorded in the database BDP associated with the module UTP. It is also possible to associate with this wish a m~;mll~ duration during which the subscriber effectively wishes to receive telephone calls. A callable independent station will thus be equipped with means suitable ~or signifying refusal or acceptance to recei~e telephone calls. Such an autonomous station can thus effecti~ely display its intention to receive calls.

The locating dialog can then in this case be the sending of a locating signal by this handset from the independent station SA to the chosen fixed terminal BFRl. This can also be a telephony c~ n; cation (incoming or outgoing) between this handset and this chosen terminal.

In practice, the database BDP stores, corresponding with the call number of the independent handset, the digital identification (for example the address), on the digital channels, of the connecting unit of terminals URBl having carried out the last location on the basis o~ a location signal sent out by the handset, as well as a designation, for example the number, of the chosen fixed tPrm;n~l BFRl where this last location took place. Each data base BDP
(here associated with a module UTP) possesses an address making it possible to contact it on the digital channels CNPU.

In response to a telephone call request from a calling fixed station SF on the switched telephone network CTPU, the specific processing means of the module UTP will establish a control link with the chosen fixed teL ; n~l ~

2~689~1 This control link comprises, after consultation of the corresponding data base BDP, a digital link between the module UTP and the terminal connecting unit URBl whose address corresponds to the location information item.
More precisely, establishment of this control link comprises sending a digital signal from the specific module UTP to the chosén terminal BFR1 by the intermediary of its connecting unit URB1. This digital signal comprises, in addition to identification of the term;n~l BFRl, an ~nstruction for a radio call by this tPrm;n~l BFRl to the independent station ~A, as well as the telephone number ABPQMCDU for a call by this tçrm;n~l BFR1 to the specific module UTP.

This telephone call from the terminal BFRl to the specific processing means of the module UTP is subject to the satisfaction of additional ' predetermined conditions.

A first additional predeterminad condition can be checking the effective capacity of the fixed term; n~l BFRl to interact with the handset. This checking can include, for example, monitoring the correct operation of this term; n~l or even its capacity to reach the independent handset SA by radio waves.

Another additional predetermined condition may also be checking the effective presence of the subscriber ready to accept the telephone call.

Moreover, the telephony-station link!has been established between the fixed station SF and the first interface of the first interfaces block of the module UTP.

When the t~rmi n~l BFRl has called the module UTP for establishment of the said primary telephony link, this call being received at the first interface o~ th~ secon~
interfaces block, the specific processing means cause 2~68~41 interconnection of these two interfaces in order to establish the telephony relationship.

As before, in parallel with this establishment, the transfer means co~m-ln;cate to the terrin~ls BFR2, BE'R3 and BFR4 adjacent to the terminal BFRl the link identifier LIDl as well as the call number ABPQMCDU of the module UTP so that this telephony relationship can possibly be switched by passing through a terminal adjacent to the tPrr;n~l BFRl.

It is appropriate also to note that, when the inter-connection is effectively set up within the specific module UTP, the primary and possibly secondary telephony links between the independent station and the specific module are recorded as being charg~d to the subscriber holding the independent handset in order to bill him as a consequence. The telephony station link established between the fixed station and the module UTP is recorded as being charged to the ~ixed station with a view to billing it.

- 20 In the case of a telephone call coming from the indepen-dent-~station to the fixed station all the telephony links established are charged to the caller.

We will refer now to ~igure 7 which illust~ates a second configuration of the network in which specific modules UTP are not provided. In contrast, the first and second interfaces blocks, the interconnection means and the specific processing means are incor~orated into at least some of the connecting units of the network~ in practice into all the connecting units. The other means of the device according to the invention remain, in this variant, installed as described a~ove.

We also assume here that the ~ixed tPrm; n~ 1 S are not directly connect~d to the telephony channels of the 206894.1 ~ network CTPU but by the intermediary of their respective connecting unit.

For the sake of simplicity in the description ik will also be assumed here that the primary and secondary fixed terminals BFRl and BFR2 are both connected by respective specialized links CCSl and CCS2 to the connecting unit URBl.

If we return now to Figure 4, it will be noted that the switching unit URBC-j of the connecting unit URB-j (here URBl) comprises, in addition to the plurality of cards MIC-j, MIC-2 for digitising the telephony signals, forming the first interfaces block, a plurality of specialized acoustic interfaces cards IAPl...IAP4 suitable for being connected to the primary and secondary fixed terminals via the specialized links CCSl and CCS2.

These cards IAPj comprise an interface with linking buses BMICS and BMIC6, followed by a converter block similar to that used in the card IRC-j, followed in turn by a telephony interface (limited to the acoustic part) on a specialized link with the tPrm; ~Al S .

The first interfaces block also comprises a plurality o~
cards ILA1, ILA2 suitable for producing an interface for connecting to telephony channels CTPR of a private cl- nications network.

These cards exhibit a structure similar to the cards IAPj, the telephony interface over a specialized link being replaced by an analog subscriber line interface with the channels CTPR in accordance with the specifications for connection to the switched telephone network.
.

All of these cards are linked together by linking buses BMI~5 and BMIC6 as well as to a switching processing unit .

20~9~
uCc-i linked to the signaling processing unit UCS-j.
This switching processing unit is, for example, produced with the aid of the MVME 117A card (already quoted), incorporating one of the software parts of the specific processing means.

When, in the case of a telephony co~ n;cation established from the independent station SA to the fi~ed station SF, the user dials the telephone number of this fixed station, on the keypad of his handset SA, the checking procedure is carried out in liaison ~ith the center CAP, in a similar way to that described aboveO

Wh~n authorization is granted by the center CAP, the primary radio frequency link is maintained between the portable handset SA and the fixed tPr~;n~l and is charac-terized in a way similar to that quoted above by the linkidentifier LID1.

The specific processing means of the connecting unit URB1 then allocate, by the intermediary of the buses BMlC, the first interface of the first interfaces block so as to reserve a telephone line for the half-call from the conn~cting unit to the station SF, so as to contribute to the establishment of the said telephony-station link.

In parallel, the specific processin~ means allocate, by the intP ?~;ary of the cards IAP-j, the first interface of the second interfaces block contributing to the establishment of the primary telephony link.
I

When these allocations are carried out, the specific processing means transmit, by the intermediary of a card CMB-j and of the signaling path of the spPcialized link CCSl, a call tone sent out by the chanr.els CTPU, to the primary tPrr;n~l-processing means of the tPrr;n~l BFRl, and cause interconnection between the first interfaces of the first and second interfaces blocks.

2~G~9~
The primary terminal-processing means then dial the telephone number of the called station SF, which will have the consequence of putting the station SA in communication with the station SF.

In the course of the telephony c-- n; cation, the first and second analysis means, here formed by software modules incorporated within the terminal connecting unit URBl, analy~e respectively the level of the primary radio frequency signal exchanged between the independent set and the first interface stage of the primary tP ; n~l BFRl, and the level of the radio frequency activity, resulting from the transmission of the primary radio frequency signal, on the radio frequency channels of the neighboring te ; n~ 1 s ~ the counterparts of the radio frequency channel of the first primary stage on which the said primary radio frequency signal is transmitted.

Needless to say that assumes that at least one of the neighboring ter~; n~l s is not saturated, that is to say that all its radio channels are not already used for other radio frequency links with other independent stations.
., When the level of the primary radio signal crosses a predetermined threshold, for example becomes less than -80 dBm, and when, in parallel, the level of the radio frequency activity on one of the neighboring terminals becomes greater than another predetermined threshold, for example of the order of -60 dBm, this ter~;n~l (assumed to be the t~rm; nal BFR2) will be selected in order to switch the telephony relationship in progress.

In order to do that, the transfer means will then commu-nicate to this ter~; n~l BFR2 the link identifier LID1.
The specific processing means will then allocate, b~ the interm~ ry of a card IAP-j, an acoustic link between this terminal BFR2 and the terminal connecting unit.

-t 2~68941 On reception of the link identifier LIDl sent out by the independent station, a channel will be selected on which the secondary radio frequency link will be established, and the specific processing means will break off the acoustic link between the first interface of the second interfaces block (at the site of a card IAP-j) and the primary terminal BFRl, then will carry out interconnection between the second interface of this second interfaces block and the first interfaces of the first interfaces block produced at the fixed station SF.

In order to avoid the term; n~l BFRl taking up the radio link again (since it also receives the identifier 1IDl sent out by the portable handset) so as to immediately generate a new switch to teL ;nAl BFR2, it can be provided for a signal to be sent to a terminal BFRl forbidding it to recognize the identifiex LIDl. Thus, only terminal BFR2 will be able to pick up the radio link.

For the user, switching this telephony relationship is perceived as reestablishment of the radio link. It will also be noted that the outgoing path is, on the contrary, not ~hanged. There is thus no break in the telephony-station link to the fixed station SF.

It ha~ been assumed here that the link identifier LIDl was co nicated to the secondary fixed terminal after the analysis carried out by the first and second analysis means. It could also be envisaged that, in parallel with the establishment of the primary li~k passing through the primary fixed terminal, the term;nAl connecting unit is already broadcasting the link identifier LIDl to the other neigh~oring terminals, that is to say before choosing a secondary fixed term; n~ 1 .

The invention also permits ensuring continuity of service, not only when the user moves, but also when the 20~8~41 external environment disturbs the radio link with the terminal, by choosing another less "disturbed" terminal, and to do this on the initiative of the independent station.

The invention is not limited to the embodiments described above but embraces all the variants contained in the scope of the claims below, especially the following:

- the two embodiments described, based on specific modules and without specific modules, are not incom-patible. In this context a network configuration couldbe envisaged in which some geographical sectors might be equipped with specific modules and other geographical sections would contain the specific means incorporated in the terminal connector units;

- the specific module UTP, or even a connecting unit, could equally be connected to a private co n; cations network also cont~in;ng private telephony channels and private digital channels;

- it is also not excluded that the use could be envi~aged, in the second variant described, of the type of predetermined conditions and/or selection criteria used in the first variant, and conversely;

- it i~ also pos~ible to include, within the module UTP
or a connecting unit, a card making it possible to send out recorded standby messages to the calling users. This card could be equipped with voice synthe~is genera~ors associated with memories~

- Telephone calls originating from a calling independent station to a callable independent station could certainly be envisaged. In this case, one of the fixed terminals interacting with one of the independent calling or called stations plays the role of the fixed station SF described 20689~1 above.

- More generally, an independent station is not limited to a telephony handset but relates to any object capable of interacting with a fixed terminal.

Needless to say, some of the means described above can be omitted in the variants where they have no function.

'

Claims (32)

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A telephony device intended to serve in a communications network between fixed stations and fixed terminals, the said fixed stations being linked to the telephony channels while the fixed terminals comprise an antenna for mutual interaction over distance with independent stations, which device comprises:

- means of interface with the antennae of a plurality of fixed terminals, - means of connection to telephony channels of the network, specific means, linked to the interface and connection means, suitable for establishing a telephony relationship between an independent station (SA) and another station (SF) linked to the telephony channels of the network, by the intermediary of a primary link between the independent station (SA) and the connecting means, via the antenna of a primary fixed terminal (BFR1), and for establishing at least one secondary link between the independent station (SA) and the said connecting means, via the antenna of a secondary fixed terminal (BFR2), chosen on the basis of predetermined selection criteria, - station-analysis means (MTS), incorporated in the independent station, suitable for generating a predetermined request information item in response to a predetermined station condition relating to the primary link, and wherein the specific means are suitable for responding to the reception of the said request information item, by switching the said telephony relationship so that it passes through this secondary link.

2. The device as claimed in claim 1, wherein the secondary fixed terminal (BFR2) is selectable among a chosen group of terminals which are adjacent (BFR2, BFR3, BFR4) to the primary fixed terminal (BFR1).

3. The device as claimed in claim 1 or 2, wherein the interface means comprise, with respectively the antennas of the primary and secondary fixed terminals, first primary (ET1-1) and secondary (ET1-2) interface stages for a plurality of radio frequency channels, wherein the specific means comprise:

- primary terminal-processing means (MPT-1; UCB-1), linked to the said first primary interface stage (ET1-1), suitable for establishing, within the said primary link, a primary radio frequency link between the independent station (SA) and the antenna on at least one of the radio frequency channels of this primary fixed terminal (BFR1), for characterizing this primary radio frequency link one-to-one by a link identifier (LID1), and for delivering this link identifier (LID1) to a second primary interface stage (MOD-1), - transfer means (URBS) linked to this second primary interface stage (MOD), suitable for receiving the said link identifier (LID1) and for communicating to a second secondary interface stage (MOD-2) a link information item (INFL) containing at least this link identifier (LID1), and - secondary terminal-processing means (MPT-2; UCB-2), linked to the said first and second secondary interface stages (ET1-2; MOD-2), suitable for establishing, within the said secondary link, a secondary radio frequency link between the independent station (SA) and the antenna on at least one of the radio frequency channels of this secondary fixed terminal (BFR2), with the aid of the said link identifier (LID1).

4. The device as claimed in claim 3, wherein the said request information item contains the link identifier (LID1).

5. The device as claimed in claim 3 or 4, wherein the first and second primary interface stages (ET1-1; MOD-1), as well as the primary terminal-processing means (MPT-1;
UCB-1) are incorporated into a primary terminal, while the first and second secondary interface stages (ET1-2;
MOD-2), as well as the secondary terminal-processing means (MPT-2; UCB-2) are incorporated into a secondary terminal.

6. The device as claimed in one of claims 3 to 5, intended to serve in a communications network comprising connecting units for fixed terminals linked, on the one hand respectively to groups of fixed terminals, and on the other hand together, wherein, the primary and secondary fixed terminals being linked to one (URB1) or two (URB1; URB2) connecting units, the transfer means (URBS) are incorporated into the said connecting unit or units.

7. The device as claimed in claim 6, intended to serve in a communications network equipped furthermore with a digital communications medium (CNPU), wherein the primary fixed terminal (BFR1) is linked to a primary one (URB1) or said connecting units while the secondary fixed terminal (BFR2) is linked to a secondary one (URB2) or said connecting units, wherein the transfer means (URBS) comprise, within the primary connecting unit, primary digital interface means (JON-1) linked to the digital communications medium of the network, and, within the secondary connecting unit, secondary digital interface means (JON-2) linked to the digital communications medium of the network, and wherein the transfer means (URBS) transmit the said link information item (INFL), between the primary and secondary connecting units, by the intermediary of the digital communications medium and of the primary and secondary digital interface means.

8. The device as claimed in one of claims 3 to 7, wherein the transfer means (URBS) communicate the said link information item (INFL) to the said secondary fixed terminal (BFR2) before reception of the said predetermined condition.

9. The device as claimed in claims 2 and 8 taken in combination, wherein the transfer means (URBS) communicate the said link information item (INFL) to all the terminals of the said group before reception of the said predetermined request information item.

10. The device as claimed in one of claims 3 to 7, wherein the transfer means (URBS) communicate the said link information item (INFL) to the said secondary fixed terminal (BFR2) after reception of the said predetermined request information item.

11. The device as claimed in one of the preceding claims, wherein the interface means comprise a first one (ET1-1) of said primary interface stages with the antenna of the primary fixed terminal (BFR1) for a plurality of radio frequency channels, wherein the specific means comprise:

- primary terminal-processing means (MPT-1; UCB-1), linked to the said first primary interface stage (ET1-1), suitable for establishing, within the said primary link, a primary radio frequency link between the independent station (SA) and the antenna on at least one of the radio frequency channels of this primary fixed terminal (BFR1), the said primary radio frequency link comprising transmission of a primary radio frequency signal on at least one of the radio frequency channels, and wherein the said predetermined station condition relates to at least one of the characteristics of the said primary radio frequency signal.

12. The device as claimed in claim 11, wherein the station-analysis means (MTS), incorporated in the independent station (SA), are suitable for analyzing the presence of a specific part of the telephony message transported by the primary radio frequency signal, and for effecting radio frequency transmission of said request information item (LDI1) in the absence of this specific part.

13. The device as claimed in one of the preceding claims, wherein the selection criteria for the said secondary fixed terminal comprise reception at this terminal of the said request information item (LID1).

14. The device as claimed in one of the preceding claims, wherein the interface means comprise, with respectively the antennae of the primary and secondary fixed terminals, first primary (ET1-1) and secondary (ET1-2) interface stages for a plurality of radio frequency channels, wherein the specific means comprise:

- primary terminal-processing means (MPT-1; UCB-1), linked to the said first primary interface stage (ET1-1), suitable for establishing, within the said primary link, said primary radio frequency link between the independent station (SA) and the antenna on at least one of the radio frequency channels of this primary fixed terminal (BFR1), the said primary radio frequency link comprising transmission of said primary radio frequency signal on at least one of the radio frequency channels, - first analysis means (MPT-1; CAN-1; DCD-1), suitable for analyzing, at the level of the first primary stage, at least one first characteristic deduced from this primary radio frequency signal, and - second analysis means (MPT-2; CAN-2; DCD-2) suitable for analyzing, at the level of the first secondary stage, at least one second characteristic deduced from the primary radio frequency signal, and wherein the selection criteria for the said secondary fixed terminal (BFR2) results from these two analyses.

15. The device as claimed in claim 14, wherein the first characteristic comprises determination of the level of the said primary radio frequency signal while the second characteristic comprises determination of the level of radio frequency activity, resulting from the transmission of the primary radio frequency signal, on the radio frequency channel of the said first secondary stage, counterpart of the radio frequency channel of the first primary stage on which the said primary radio frequency signal is transmitted.

16. The device as claimed in one of the preceding claims, wherein at least the primary and secondary fixed terminals comprise respectively third primary (IRC-1; MOD-1) and secondary ( IRC-2; MOD-2) interface stages linked respectively to the primary and secondary terminal-processing means, wherein the connecting means comprise:
- a first interfaces block (MICi) linked to the telephony channels of the network, - a second interfaces block linked (MICj; 1APj) to some at least of the fixed terminals of the network, - interconnection means (BMICj) between these interfaces, - wherein the specific means comprise specific processing means (UCM; BUC-M) linked to these interface blocks as well as to the interconnection means, wherein the specific means are suitable for establishing a telephony - station link between a first interface of the first block and the said other station (SF), a primary telephony link between the third primary interface stage (IRC-1) of the primary terminal and a first interface of the second block, and a secondary telephony link between the third secondary interface stage (IRC-2) of the secondary terminal and a second interface of the second block, and establishing the said telephony relationship by authorizing interconnection between the first interface of the first block and the first interface of the second block, then for authorizing interconnection between the said first interface of the first block and the second interface of the second block in order to switch the said telephony relationship.

17. The device as claimed in claim 16, wherein, while there is a telephony relationship from the independent station (SA) to the said other station (SF):

establishment of the said primary telephony link results from a primary call signal from the third primary interface stage (IRC-1) of the primary terminal to the second interface block, the specific processing means are suitable for allocating, in response to this primary call signal, the said first interface of the first block, then for carrying out interconnection between this first interface of the first block and the first interface of the second block and for transmitting a dialling authorization signal to the said primary fixed terminal (BFR1) so that the latter composes the telephone number of the said other called station (SF).

18. The device as claimed in claim 17, wherein the third primary (IRC-1) and secondary (IRC-2) interface stages are linked to the telephony channels of the network while the second interfaces block is connected to the telephony channels of the network.

19. The device as claimed in one of claims 16 to 18, wherein the secondary terminal-processing means, incorporated in the secondary fixed terminal (BFR2), are suitable for sending a secondary call signal in the said second interface of the said second block, after reception of the said link identifier (LID1) in the said first secondary stage.

20. The device as claimed in claim 19, wherein, as the station-analysis means transmit at least once the said link identifier (LID1), the primary terminal- processing means are suitable for sending the said secondary call signal after a predetermined time interval starting on first reception of the said link identifier (LID1) in the said first secondary stage.

21. The device as claimed in claim 14 and one of claims 16 to 18 taken in combination, wherein in the presence of said primary radio frequency signal exceeding a predetermined primary threshold, and in the presence of a level of radio frequency activity exceeding a predetermined secondary threshold, the specific processing means are suitable for transmitting to the secondary terminal-processing means (MPT-2); UCB-2) a control information item in order to permit establishment of the said secondary radio frequency link.

22. The device as claimed in one of claims 16 to 21, which comprises a specific module (UTP) incorporating at least the first and second interfaces blocks, the interconnection means and the specific processing means.

23. The device as claimed in claims 3 and 22 taken in combination, intended to serve in a communications network equipped in addition with said digital communications medium, wherein the specific module (UTP) comprises a digital interfaces block linked to the said medium, and wherein the transfer means (URBS) are suitable for communicating the said link information item (INFL) to the said module by the intermediary of the digital communications medium.

24. The device as claimed in claim 22 or 23, wherein the said link information item (INFL) comprises, in addition to the said link identifier (LID1), a station identifier suitable for the independent station (SA) as well as a telephone call number of the specific module (UTP) suitable for being received in the said first interfaces block of this specific module (UTP).

25. The device as claimed in claim 24 taken in combination with one of claims 19 and 20, wherein the secondary terminal-processing means of the secondary fixed terminal (BFR2) send the said secondary call signal with the aid of at least a part of the said call number.

26. The device as claimed in one of claims 22 to 25 taken in combination with claim 18, wherein the specific processing means are suitable for responding to a telephone call request from the said other station (SF) to the independent station (SA), the said call request being received in the said first interface of the first interfaces block:

by seeking to establish, in addition to the telephony-station link, the said primary telephony link between the third primary interface stage (ET1-1) of the primary fixed terminal (BFR1) and the said first interface of the second interfaces block, on the basis of predetermined supplementary conditions, and on the basis of an information item for localization of the said primary fixed terminal (BFR1).

27. The device as claimed in one of claims 22 to 26, wherein the first and second interfaces block comprise a plurality of cards (MICj) for digitization of the telephony signals, linked by at least one link bus (BMIC3, BMIC4) forming the interconnection means, wherein the said link bus is suitable for transporting digital data using a frame subdivided into a plurality of time intervals (ITO, ....IT31) comprising usable intervals and signaling intervals (ITO; IT16), and wherein the specific processing means are suitable for acting on at least one of the signaling intervals (IT16) in order to permit reception or transmission of a telephone call in or from the first and second interface blocks.

28. The device as claimed in one of claims 16 to 21, taken in combination with claim 6, wherein the first and second interfaces blocks, the interconnection means and the specific processing means are incorporated in at least some of the connecting units of the network.

29. The device as claimed in claim 28, wherein the second interfaces block comprises a plurality of specialized acoustic interfaces cards suitable for being connected to the primary and secondary fixed terminals by a specialized link, and wherein the first interfaces block comprises a plurality of cards (MICi) for digitising the telephony signals, linked together and to the acoustic interface cards by at least one link bus (BMIC3, BMIC4) forming the interconnection means.

30. The device as claimed in one of the preceding claims, wherein the communications network is a private network.

31. The device as claimed in one of claims 1 to 29, wherein the communications network is a public network.

32. Method of telephony interconnection, intended to be employed in a communications network between fixed stations and fixed terminals, the said fixed stations being linked to the telephony channels while the fixed terminals comprise an antenna for mutual interaction over distance with independent stations, in which method there is provided:

- means of connecting to the telephony channels of the network, - there is established a telephony relationship between an independent station (SA) and another station (SF) linked to the telephony channels of the network, by the intermediary of a primary link between the independent station (SA) and the connecting means, via the antenna of a primary fixed terminal (BFR1), there is chosen a secondary fixed terminal (BFR2) on the basis of predetermined selection criteria, there is established a secondary link between the independent station (SA) and the said connection means, via the antenna of the said secondary fixed terminal (BFR2), in response to a predetermined station condition, relating to the said primary link, there is generated, from the independent station a predetermined request information item (LID1), and in response to reception of the said request information item, the said telephony relationship is switched so that it passes through this secondary link.