fig1 represents a terminal 10 , which is preferably a personal computer ( pc ) with its keyboard and screen , connected to a communications network 20 which can simply be the telephone network . a modem 30 is classically interposed between the pc and the network to ensure that the data to be transmitted from the pc to the network conform to a standard acceptable to this network . other terminals are disposed at other input - output points of the network and a modem is interposed between each terminal and the network . a communication can thus be established between two pcs . the modem can be built into the pc ; it is generally then a specialized peripheral card in the pc ; or it can be in a housing separate from the computer , connected to a serial communications port of the pc . the various functions of the modem are established by a microcontroller which constitutes the intelligent kernel of the modem . this microcontroller has a microprocessor ( capable of receiving and executing sets of instructions ) and memories , particularly at least one read only memory which contains programs or subprograms for the microprocessor . the various programs correspond to the various outgoing or incoming communication functions that the modem may have : communication establishing routines ( calling , dialing , auto answer , etc . ), error correction , redundancy , and data compression procedures , operating in fax mode , etc . these programs and subprograms in the microcontroller memories are what are called the firmware of the modem , namely the fixed software physically built into the equipment . these integrated programs are activated by a command from the pc . for this purpose the latter provides the microcontroller with commands ( in the computer processing sense of the term ), namely orders to run executable subprograms , and these commands can either be entered directly from the pc keyboard by the user or furnished by the memories of the pc . the microcontroller interprets these commands , usually received in ascii format , and executes them by running the appropriate program or programs . in practice , almost all modems operate with commands known as at commands or hayes commands . each command has a sequence of several keyboard characters and all the sequences begin with the string of two consecutive characters , namely of the character ‘ a ’ followed by the character ‘ t ’. the command ends with the character representing the “ carriage return ” or “ enter ” on a classical keyboard . as soon as the modem microcontroller receives the ‘ at ’ sequence , it knows that the command is intended for it , registers it , and waits for the end ( carriage return ) to execute it . as previously explained , if the ‘ at ’ sequence is followed by the ‘+ f ’ sequence , the microcontroller knows that it must configure the modem in “ fax ” mode and the programs it will execute will correspond to a fax transmission protocol . certain modems do not have this “ fax ” mode . fig2 shows the classical schematic configuration of a modem with a pc communications interface circuit 40 ( generally a serial communications interface circuit ), a microcontroller 50 , a specialized signal processor 60 constituting the data pump , namely the modulation / demodulation circuit proper controlled by the microcontroller , and a line interface circuit 70 ( serial communications interface ) connected to the network . fig3 shows schematically the configuration of a modem according to the invention . the modem has the same elements as in fig2 and also physical elements proper for constituting a smartcard reader , but the kernel of this reader is not a specific microcontroller programmed as a card reader , but is microcontroller 50 of the modem which has built - in software ( firmware ) appropriate for communication between the card and the pc . the additional elements added relative to fig2 are , in addition to specific supplementary programs of the microcontroller firmware , a receptacle 80 for receiving a card with an insertion slot 90 , a connector in this slot , and a card interface circuit controllable by the microcontroller . fig4 shows schematically card interface 100 , connector 110 , and card 120 with contacts 130 that can be opposite connector 110 when the card is inserted into its receptacle . to facilitate the use of the smartcard in association with the modem , it is provided not only that the same microprocessor form the kernel of the modem and the kernel of the card reader , but it is also provided that the commands from the pc for communication with the card form a subset of the modem commands . in other words , in the typical case where the modem commands necessarily begin with the sequence ‘ at ’, it is provided that the communication commands with the card also necessarily begin with the sequence ‘ at ’. in order for the microcontroller to determine that this is a communication command with the card , it is preferably arranged that any card communication command begin with the sequence ‘ at + g ’ and end with an ascii character corresponding to the carriage return . the rest of the sequence , before the carriage return , precisely defines the commend requested . it will hence be understood that the modem of the invention is provided with internal programs such that : its microcontroller reacts to a two - character sequence ‘ at ’ by considering the next sequence as a command ; the same microcontroller reacts to a four - character sequence ‘ at + g ’ by considering the next sequence up to the next carriage return character as a card communication command . the general principles adopted for card communication commands are preferably the following ( other than the general principle of beginning any sequence with the sequence ‘ at + g ’ and the general principle of ending with a carriage return character ): the commands are accepted in upper case or in lower case ; the microcontroller thus interprets an ascii character corresponding to a lower - case alphabetical character and the ascii character corresponding to the same alphabetical character in upper case , identically ; interpretation of the command does not begin until after the carriage return ; the card commands cannot be chained : a command is not accepted until the previous command has been fully executed and until any response has been transmitted ; on the contrary , operating commands from the modem for communication with the network can be chained ; the number of characters contained in one command line cannot exceed 256 ; the command proper can be accompanied by mandatory or optional parameters allowing it to be executed ; the equals sign ‘=’ is a separator indicating the presence of parameters associated with the command ; it is placed after the command proper ; if there are several parameters , they are separated by a comma (‘,’); a parameter can be constituted by one or more octets without a separator ; the command octets received by the microcontroller are expressed in hexadecimal and each is constituted by two ascii characters ; they can be input from the pc keyboard and transmitted as such to the microcontroller . the card communication commands normally evoke responses . the format of the responses sent by the modem to the terminal in the case of a communication with the smartcard is the following : the card responses are of a single type ( extended ) and cannot be suppressed ; each response begins and ends with a carriage return followed by the sequence ‘ lf ’; a response can be constituted by one or more parameters separated by a comma an ‘ error ’ response is sent if the command has a syntax error or if one or more parameters are wrong . several main commands that can be used to operate the modem according to the invention for its communication function with a smartcard will now be provided , and the associated responses will also be given . commands between the pc and the network are classical hayes commands . to turn on a card and reset ( reinitialize ) it , the ‘ at + gon ’ command is sent ; it is followed by a parameter t1 ( value between 0 and 255 ) defining the card insertion waiting time . the command is ‘ at + gon = t1 ’. the response sent by the modem microcontroller to the terminal is composed of the sequence ‘ ts ’ followed by at most 32 characters . these characters can be the following parameters : to ( format character ), tai , tbi , tci , tdi ( interface character ), t1 , t2 . . . tk ( history characters ), tck ( control character ). hot reset ( without turning off ) is controlled by the sequence ‘ at + gwr ’. without going into details of the communication protocols between a card reader and a card , it will be recalled that the iso7816 standards call for dialog commands between the reader and the card ; these commands are grouped under the designator apdu . by analogy , a command prefix ‘ at + gpdu ’ is created here and this , when sent by the terminal to the modem microcontroller , indicates that an apdu type command is to be sent to the card . the command sent will obey the following rules after the prefix sequence ‘ at + gpdu ’ and before the carriage return : the header includes successive values cla , ins , p1 , p2 , each represented by an octet ( two ascii characters ); each value is between 0 and 255 ; cla is the instruction class ; ins is the instruction code , and p1 and p2 are parameters ; the body of the instruction has three fields : lc , data , and le . the lc field contains the number of words present in the data field ; data is the data field proper to be transmitted ; “ le ” is the number of words expected in the response . is a write request ( data accept instruction da ) to address 02a0 of a field of two ( 2 ) octets including the characters 6d and 6c . the response is composed of an optional body which is a data field representing a number of words received , and a mandatory ending including two octets sw1 , sw2 called “ command processing status ” and “ command processing qualifier ”; these two octets represent the fact that the command is correct and there is no error in the data . other than a write request ( da ), other commands of the apdu type are possible , for example a read request for a zone of the card , a signature calculation request by the card , etc . the command is an inquiry about the type of card inserted . the command is ‘ at + gi ’. it is not followed by parameters . the response is a group of two octets r1 , r2 representing the type of coupler and the type of card respectively . turning off is done by ‘ at + goff ’ command without a parameter . the response is the octet r1 defining the type of coupler . the card register configuration can be commanded by the terminal . the command is ‘ at + gsr ’ followed by the parameters s1 , s2 , s3 which define the registers to be activated (“ set register ” command ). the response is a string of octets confirming this activation . this defines the principal commands that can be sent by the terminal for the modem microcontroller and which are understood as instructions for communication with a smartcard inserted into the insertion slot associated with the modem . card interface circuit 100 which is controlled by the microcontroller upon reception of these commands is constituted in classical fashion ( namely like a classical card reader ) such as to establish signals according to a classical communication protocol between a card and its reader . reference may be made to iso 7816 for the format of these signals and hence for constituting the interface circuit . the card connector generally has 6 or 8 contacts including at least the following contacts : clk ( clock ), i / o data , rst ( reset ), vcc ( power supply ), and gnd ( ground ). these contacts are shown in fig4 . in one application to local modem utilization security , it is the pc that manages this security , access to the modem being authorized if the pc has ascertained that a smartcard has been introduced into the modem and the secret code corresponding to this card has been keyed in by the user . in this case , the procedure may be as follows : the pc security program asks the user to insert a card into the modem and for example sends an instruction of the ‘ at + gon ’ type to the modem microcontroller ; when the card is present , it sends a response ( in a communication protocol between reader and card ) and this response is sent by the microcontroller to the pc ( in the pc protocol ; the pc asks the user to enter his secret code using the keyboard ; it sends this code to the card by an instruction beginning with ‘ at + g ’; the card verifies this code and sends an accept or refuse response ; the modem microcontroller sends this acceptance or refusal and the pc authorizes or fails to authorize its “ modem ” peripheral for the network communication functions depending on acceptance or refusal . in another application , the card is used to authorize access or transactions with a party on the network . this is not a local mode security application but a remote mode security application . for example , the pc is used to access an on - line database managed by a server , with the access being authorized if the user is indeed an authorized subscriber , provided for this purpose with a smartcard and a secret code which he alone possesses . the card is then preferably a card with response calculation algorithms involving at least one secret key contained in the card . the pc establishes the link with the network by ‘ at ’ commands sent to the modem ( but not ‘ at + g ’ commands ). the database server starts a control procedure consisting of asking the pc to furnish a response to a random datum . the correct response can be sent only if the pc user uses simultaneously the random datum , a secret key contained in the card , and a secret code possessed by the user . the correct response can be calculated by the server which knows its subscribers and thus knows the secret keys , the secret codes , and the random data they send . a comparison of responses by the server will authorize access to the database . in this case , after the pc has received a random datum from the server , it starts a dialog with the card by commands of the ‘ at + g ’ type ; the pc sends the random datum to the modem microcontroller ; the latter sends it to the card in the card communication protocol ; it does the same for a secret code that the pc asks the user to enter ; the card calculates a response , sends it to the modem microcontroller , which transmits it in its turn to the pc ; then the pc sends it to the network by an ‘ at ’ type command not followed by the prefix ‘+ g ’. the server then checks the accuracy of the response and authorizes access to the database or refuses such access . the procedure would be similar for making a transaction validated by the fact that an accurate response is furnished by the card in response to a random datum . since it is the same microprocessor that controls the communication with the network and the communication with the card , it may be that the microcontroller responds directly to a specific command from the network ( not from the pc ) to transmit the random datum directly to the card , or perform other communication operations with the card without going via the pc . for example , if procedures using the card do not require entering a secret code via the keyboard , such operations may be performed directly , facilitated by the fact that it is the same microcontroller that controls both the modem and the card . a novel modem design has been described , offering more options than in the prior art , which is less expensive , and more practical for the user since the communication syntax can be essentially the same for the modem and for the card . secure access to in - house networks from outside networks such as the internet ; card - controlled banking at home ; bill paying ; purchase and sale of securities ; secure automatic connection to databases or to software help servers providing software upgrades , remote troubleshooting , etc .