Patent Publication Number: US-7587470-B2

Title: Internet modem streaming socket method

Description:
RELATED APPLICATIONS 
   The present application is a continuation of a patent application filed Aug. 11, 2005 under Ser. No. 11/203,471, now U.S. Pat. No. 7,302,499, which is, in turn, a divisional of an application filed Sep. 27, 2001 under Ser. No. 09/965,952, now U.S. Pat. No. 7,039,717, which, in turn, claims the priority benefit of a provisional application filed Nov. 10, 2000 under Ser. No. 60/247,265, all of which are Incorporated herein by reference. 

   TECHNICAL FIELD 
   The Invention relates generally to Internet communication technology, and more particularly to a system and method that provide streaming socket connection between Internet client and Internet server through an Internet modem. 
   BACKGROUND OF THE INVENTION 
   A standard modem can be in either one of two modes, command mode or data mode. In a command mode, no data is passed across the modem. The modem operation is controlled using standard modem “AT” or other commands. When the modem is connection to another modem, it goes into data mode. Changing back to command mode can be done with an escape sequence. 
   As for any standard modem, the following guidelines are used when issuing commands:
         When using “AT” commands, start every command line (except the “A/” and “+++” commands) with an attention (“AT”) code characters. Otherwise, the modem will not execute the command.   The commands following the “AT” prefix can be uppercase, lowercase, or a combination of both.   Always type the “AT” prefix in the same case (not “At” or “aT”)   Telephone numbers may be entered with or without punctuation.   Commands must be terminated with a carriage-return character. This is typically ASCII 13 (0x0D). However, it can be changed by modifying the modem S-Register number 3.       

   Each command line to a modem has the following format (with the exception of the “A/” and “+++” commands):
 
&lt;AT&gt;&lt;Command&gt;{Argument} {=n} { }
 
   Wherein “&lt;AT&gt;” is the attention code, “&lt;Command&gt;” is a command consisting of one letter of an ampersand (“&amp;”), percent (“%”), or backslash (“\”) followed by a letter, “{Argument}” is optional information specific to the Command, and “{=n}” is used in some instance to qualify an Argument specific to the Command. The information in angle brackets (“&lt; &gt;”) must be included as part of the command line, while information in curly braces (“{ }”) may or may not be necessary as part of the command line. It is also possible to string commands together in one command line. The attention code “AT” is only required at the beginning of the command line. 
   In the command mode, characters received from the serial port are interpreted as commands and must follow the guidelines described above. The modem transitions from the command mode to the data mode after a successful “ATD” command or after receiving a call in auto-answer mode. To transition from the data mode to the command mode, an escape, either a sequence of characters or toggling the DTR line, must be sent to the modem. This sequence is typically “+++”, however, this can be changed to another repeated character by modifying the modem S-Register number 2. Typically, a delay with no data transfer of one second before and after this escape sequence is required. This time delay can be changed by modifying the modem S-Register number 12. The “ATO” command is used to resume the data mode without having to hang-up and redial. 
   A separate TCP socket application is usually added to establish Internet connection once the modem is in data mode. However, it is often desirable that a TCP streaming socket can be opened on the modem so that an Internet client can directly communicate with an Internet server over the socket. 
   SUMMARY OF THE INVENTION 
   The streaming sockets technology according to this invention offers power and flexibility that are not garnered by traditional service based on batch commands excited in command mode. 
   A streaming socket is a highly efficient way of utilizing a TCP socket over an asynchronous or synchronous serial data channel like an RS-232 serial port without the need for complex framing or encapsulation. It allows the client device to send and receive data over a TCP socket by simply reading and writing characters on the data channel. The streaming-socket doesn&#39;t need to know beforehand how much data is going to be exchanged, it simply allows a free flowing stream of data between the TCP socket and the client over the data channel. It also incorporates the concept of a streaming socket timer that allows the streaming socket to efficiently packetize the serial data stream into TCP segments. The socket streaming timer is tunable to provide maximum efficiency when utilized from various types of data sources, whether interactive or machine driven. Streaming sockets are also an effective way to share the data channel with many TCP sockets. 
   An Internet modem provides full modem functionality in addition to the Internet connectivity. The interface to the Internet modem is identical to that of a standard modem. Standard “AT” modem commands can be issued to the Internet modem and the behavior is the same as it is for a standard modem. 
   The internet modem is an extension of the command mode and data mode idea used in standard modem. In an Internet ready modem, there are two Internet session modes besides the standard command mode and data mode. The Internet session modes are Internet session command mode and Internet session streaming socket mode. The standard command mode and data mode are same as these of a standard modem. A “T” command or an “R” command enables Internet session streaming socket mode. Once in Internet session streaming socket mode, any data sent to the Internet modem is sent across the TCP socket, and data received on the socket is sent from the modem. Internet session streaming socket mode can be terminated by the standard modem escape sequence or by toggling the DTR. Once in Internet session command mode, the last streaming socket can be resumed, or another streaming socket can be started or resumed. 
   The Internet modem dials up an Internet Service Provider (ISP) and uses data mode to send a username and password string to the ISP. Once the username and password have been accepted, it returns to command mode by escaping out of data mode. Once back in data mode, PPP is raised, a TCP connection is initiated and Internet session streaming socket mode is entered. The TCP transaction is completed via the streaming socket. Once completed, Internet session streaming socket mode is escaped back into Internet session command mode where the socket can be closed and more commands can be executed. 
   Several streaming sockets can be used at the same time by escaping out of one streaming socket and creating or entering another streaming socket. 
   The communication method provides a straightforward way to transmit and receive data with an HTTP server. This is not limited to HTML content because any ASCII data can be transmitted via HTTP. The use of CGI can make this a powerful tool. Alternatively, an Internet client can use the Internet modem to communicate to an SMTP server. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block schematic diagram showing a computer network comprising an Internet server and an Internet client that contains an Internet modem; 
       FIG. 2  is a flow diagram of a method for establishing the communication between the Internet client and the Internet server through the Internet modem; 
       FIG. 3  is a diagram showing sample command sequence to establish a TCP connection over a streaming socket; 
       FIG. 4  is a state transition diagram for the Internet ready device; and 
       FIG. 5  is a state transition diagram showing the flow from connecting a TCP socket to a streaming socket, using the streaming socket and closing streaming socket. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A. The Communications Network 
     FIG. 1  is a block schematic diagram that illustrates a computer network  10  comprising of an Internet client  11 , an Internet modem  12 , and an Internet server  18 . The Internet modem  12  contains a Streaming Socket  13 , a command processor  14  that interprets an Internet ready command line interface, and a TCP/IP stack  15 . 
   The Internet client  11  communicates with the Internet modem  12  through the Internet Ready command line interface over an RS-232 serial port  17 . The command processor  14  instructs the TCP/IP stack  15  to open and close sockets, send and receive data, and provide other network functionality. The command processor  14  can also switch the Internet modem to Internet session streaming socket mode where the streaming socket  13  is attached directly to an open socket in the TCP/IP stack  15  and the serial port  17 . The streaming data is sent from the Internet modem  12  to the Internet server  18  through a phone system  18 . 
   The Internet modem  12  also contains the following Internet specific S-Registers:
         S0-S1: Socket 0/1 Status       

   These registers read the operating status of the two physical sockets in the Internet modem  12 . They each contain a 3-character string that represents their current status. These registers are read-only. Any attempt to write to them will fail silently.
         S2-S3: Socket 0/1 Source Port       

   These registers read the source port of the two physical sockets in the Internet modem  12 . They are either set by a parameter in a “T” command or randomly generated if the parameter is omitted. These registers contain a character string that represents the port number. Valid port numbers are between 1 and 655535. These registers are read-only. Any attempt to write to them will fail silently.
         S4: IP Address of Internet Modem       

   This register stores the local device IP address. If the Internet modem is used with a static IP address, this register must be set with a valid address before the “C” command is executed. If this value is not set before “C” command is executed, the Internet modem  12  negotiates a valid “IP” address during PPP negotiations. In that case, the value is only valid while PPP is active, between the execution of a “C” command and “D” command. It then shows the current negotiated IP address for the Internet modem  12 . The register contains a character string that represents the IP address. The string is in the “dotted decimal” format: xxx.xxx.xxx.xxx (i.e. 192.168.2.10). When the IP address is invalid, it returns the invalid IP address: 0.0.0.0.
         S5: Primary DNS Server       

   This register stores the primary DNS server address. If the register is not set, hostname lookups will fail. The register contains a character string that represents the IP address. The string is in the “dotted decimal” format: xxx.xxx.xxx.xxx (i.e. 192.168.2.10). When the IP address is invalid, it returns the invalid IP address: 0.0.0.0.
         S6: IR Configuration Byte       

   This register returns or can be set with a ASCII hex byte. The byte is assembled with the following bits:
         0x01=Echo in Command Modes (0=off\1=on(default))   0x02=Echo in Streaming Socket Mode (0=off\1=on(default))   0x04=Result Codes Verbose (0=off\1=on(default))   0x08=Internet Mode Escape Sequence (inband escape) (0=off\1=on(default))   0x10=Internet Modem Data Mode Escape (0=off\1=on(default))   0x80=Debug Streaming Socket Marker (0=off(default)\1=on)   S7: TCP Stream Tick Time       

   This register contains the TCP Stream Tick Time used to determine when to send TCP segments. Valid range is 0 through 255 units. Each unit is equal to 10 ms. Default is 50. 
   SE: EEPROM Read/Write/Play Slots 
   This register lets the user take advantage of non-volatile memory that may exist on the device. The EEPROM memory is divided up into slots of 32 characters each. The number of slots available is dependent on the system design, typically 8 or 16. Slot  0  is a special slot that is automatically executed on modem power-up and is useful to set the modem in a default state on power-up. Slots can be used for AT commands, IR commands, or for user storage. Data can be written to slots, read from slots, or sent to the IR and AT command processors for “playback”. Multiple commands can be stored for playback in one slot if separated by the “&#39;” (backward single quote) character. 
   For example: 
   To store a reset modem command and DNS server init command that will execute on reset:
 
irse0=ATZ′irs5=192.168.1.1
 
   To echo slot zero back:
 
irse0
 
   To playback slot  1  to the IR and AT command processors:
 
irse1!
 
   To store a dial string in slot  2 :
 
irse2=ATDT9,5559874
 
B. The Command Line Interface
 
   The Internet modem  12  extends the standard modem modes with two additional Internet session modes. When the Internet modem  12  is not in the Internet session modes, it behaves exactly like a standard modem, and can be in either the command mode or data mode. In the Internet session modes, the Internet modem  12  can be in either Internet session command mode or Internet session streaming socket mode. However, the Internet modem  12  does not behave exactly like a modem in these two modes. In Internet session command mode, characters received from the serial port are interpreted as commands and must follow the guidelines described above. In this case, only “IR” commands are interpreted by the command processor  14 . Standard modem “AT” commands are not supported in this mode. In Internet session streaming socket mode, the Internet modem receives characters from the serial port, converts the data to Internet protocol packets, then converts them to analog signals and transmits these signals over the telephone line. 
   The Internet ready command line interface accepted by the command processor  14  consists of several “IR” commands. These “IR” commands follow the same guidelines as the stand modem “AT” commands:
         When using “IR” commands, start every command line (except the “+++” commands) with the Internet ready (“IR”) code characters.   The commands following the “IR” prefix can be uppercase, lowercase, or a combination of both.   Always type the “IR” prefix in the same case (not “Ir” or “iR”).   Commands must be terminated with a carriage-return character. This is typically ASCII 13 (0x0D). However this can be changed by modifying the modem S-Register number 3.       

   Each command line to a modem follows the format:
 
&lt;IR&gt;&lt;Command&gt;{Argument}
 
   Wherein “&lt;IR&gt;” is the Internet ready code, “&lt;Command&gt;” is a command consists of one letter, and “{Argument}” is optional information specific to the Command. The information in angle brackets (“&lt; &gt;”) must be included as part of the command line, while information in curly braces (“{ }”) may or may not be necessary as part of the command line. For the “IR” commands, it is not possible to string commands together in one command line. 
   The Internet ready command line interface  14  includes the following “IR” commands:
         “C” Command to Initialize the Connect Mode       

   This command starts device connection and negotiates PPP. It may take some time to return. When finished, the Internet modem transitions to Internet session command mode. Only “IR” commands can be sent to the Internet modem after this command executes. The syntax of this command is
 
IRCn{username, password}
 
   Wherein n can be 0 or 1 with a default value of 0. When n is set to 1, PAP authentication is used, and therefore the username and password must be provided. The username and password represents the PAP authentication user name and password respectively. The possible responses that may be returned include:
         “CONNECT” (1): Connection is established   “ERROR” (4): Invalid command format   “PPP FAILED” (80): PPP negotiation failed   “D” Command to Terminate the Connect Mode       

   This command starts device termination and device terminates PPP. When finished, the Internet modem  12  transitions to standard modem command mode. The syntax of this command is
 
IRD
 
   No parameters are needed for this command. The possible responses that may be returned include:
         “OK” (0): Command executed. Return to standard modem command mode   “ERROR” (4): Invalid command format   “PPP DOWN” (81): PPP is not up   “T” Command to Connect to TCP Server       

   This command starts device connection to server through TCP socket. When finished, the Internet modem transitions to Internet session streaming socket mode. Any data sent to the serial port is sent through the open TCP socket. To return to Internet session command mode, the Internet modem must be escaped or the server must terminate the TCP connection. The syntax of this command is
 
IRTn,&lt;server:port&gt;{;}
 
   Wherein n can be 0 or 1 to specify the socket number to connect, server is the IP address or name of the server to connect to, port is the TCP port number on the server to connect to. If the last character on the command line is a semicolon, the Internet modem  12  returns to Internet session command mode rather than the Internet session streaming socket mode. The connection is still created and alive. The possible responses that may be returned include:
         “OK” (0): Command executed. Return to command mode.   “CONNECT” (1): Connection is established   “ERROR” (4): Invalid command format   “PPP DOWN” (81): PPP is not up   “TCP FAILED” (82): TCP negotiation failed   “SOCKET INUSE” (85): Socket already in use   “SOCKET RESET” (86): Socket reset by peer   “R” Command to Resume Socket Connection       

   This command resumes Internet session streaming socket mode with the selected socket. The socket must have been connected with either a “T” command with a “;”, argument, or “T” command and then escaped with “+++”. The Internet modem  12  transitions to Internet session streaming socket mode. To return to Internet session command mode, the Internet modem  12  must be escaped or the server  18  must terminate the TCP connection. The syntax of this command is
 
IRRn
 
   Wherein n can be 0 or 1 to specify the socket number to resume. The possible responses that may be returned include:
         “OK” (0): Command executed. Return to command mode   “CONNECT” (1): Connection resumed   “ERROR” (4): Invalid command format   “PPP DOWN” (81): PPP is not up   “SOCKET DOWN” (84): Socket not connected   “X” Command to Release Socket Connection       

   This command closes the selected socket and releases the socket resources. The syntax of this command is
 
IRXn
 
   Wherein n can be 0 or 1 to specify the socket number to release. The possible responses that may be returned include:
         “OK” (0): Command executed   “ERROR” (4): Invalid command format   “PPP DOWN” (81): PPP is not up   “SOCKET DOWN” (84): Socket not connected   “U” Command to Allocate UDP Socket       

   This command sets up a socket resource to allow UDP communications. The syntax of this command is
 
IRUn,&lt;port&gt;
 
   Wherein n can be 0 or 1 to specify the socket number to allocate, port is the UDP port number to listen for packets on. The possible responses that may be returned include:
         “OK” (0): Command executed.   “ERROR” (4): Invalid command format.   “PPP DOWN” (81): PPP is not up.   “SOCKET BUSY” (90): Socket is already in use and must be released first.   “G” Command to Get UDP Data From Socket.       

   This command returns a UDP datagram from socket if it exists. The syntax of this command is
 
IRGn
 
   Wherein n can be 0 or 1 to specify the socket to check for data on. The possible responses that may be returned include:
         “OK” (0) ip:port, len: [data]cr/lf: Datagram is available and returned, wherein ip is 4 bytes, port is 2 bytes, len is 2 bytes and data is len bytes   “ERROR” (4): Invalid command format   “PPP DOWN” (81): PPP is not up   “NO DATA” (81): No data is waiting   “SOCKET DOWN” (81): Socket not allocated       

   “P” Command to Put Data Out UDP Socket 
   This command sends a UDP datagram containing desired data. The syntax of this command is
 
IRPn, &lt;server:port&gt;, &lt;len: [data]&gt;
 
Wherein n can be 0 or 1 to specify the socket to send data to, server is the IP address or name of the server to send datagram to, port is the UDP port number to send datagram to, len is 2 byte to specify the length of data. The possible responses that may be returned include: “OK” (0): Datagram was sent “ERROR” (4) Invalid command format “PPP DOWN” (81): PPP is not up “NO DATA” (81): No data is waiting “SOCKET DOWN” (81): Socket not allocated
         “S” Command to Set or Show S-Register       

   This command is used to set and show the Internet specific S-Registers of the Internet modem  12 . The registers are used to store various operating parameters of the Internet modem  12 . The syntax of this command is
 
IRSn?, IRSn=y
 
   Wherein n specifies the Register number to access, y is the new value to set the register to.
         “O” Command to Turn Off Internet Session Modes       

   This command turns off the Internet session modes. It can not be turned back on except by reset the power. The syntax of this command is
 
IRO
 
   A result code is issued from the Internet modem  12  for standard “AT” commands as well as “IR” commands. The result codes may be issued in either of two possible formats: words (the long form, also known as verbose) or numeric characters (the short form, represented by digits). The result code format is set using the “ATV” command, ATV 1  (default) for words, and ATV 0  for numeric characters. 
   Word result codes are preceded and followed by a carriage-return (typically ASCII 13 (0x0D)) and line-feed (typically ASCII 10 (0x0A)) character. These characters are defined by modem S-Registers numbers 3 and 4. Numeric character result codes are terminated by the same carriage-return character that command lines are terminated with (ASCII 13 (0x0D)). 
   One can modify or change the values of an S-Register from the command mode with the “ATSn=” command. One can read the current value of an S-Register from the command mode with the “ATSn?” command. 
   The command processor  14  interprets some standard modem “AT” commands that modify the command mode interface. These include “ATE” for setting the echo mode, “ATV” for changing the result code format, and “ATS” for changing the interface command characters. These commands affect the command mode for both the “AT” commands and the “IR” commands. 
   C. Connect Internet Client to Internet Server 
   Now referring to  FIG. 2 , illustrated is a flow diagram  20  of a method for establishing the communication between the Internet client  11  and the Internet server  18  through the Internet modem  12 . The method includes the following steps:
           21 . Checking whether an Internet modem is present.
           Command to Modem: IR   Response from Modem: OK         22 . Dialing the modem to a destination number switching modem to data mode.
           Command to Modem: ATDTl4089614565   Response from Modem: CONNECT   The sample command is shown as  301  and the response is shown as  302  in the command sequence diagram ( FIG. 3 ).         23 . Escaping the Internet modem from data mode to command mode.
           Command to Modem: +++   Response from Modem: OK   The sample command is shown as part of  302  in the command sequence diagram ( FIG. 3 ).         24 . Connecting to the POP and negotiating a PPP connection using the “C” command and switching the Internet modem  12  to Internet session command mode.
           Command to Modem: IRClusername, password   Response from Modem: CONNECT   The sample command is shown as  303  in the command sequence diagram ( FIG. 3 ).         25 . Connecting to the Internet server  18  using the “T” command and establishing a TCP socket connection for one streaming socket.
           Command to Modem: IRT0, 192.168.1.20:80, 4321   Response from Modem: CONNECT   The sample command is shown as  304  in the command sequence diagram ( FIG. 3 ).         26 . Performing necessary Internet transactions between the Internet client  11  and the Internet server  18 . This step is also shown as  305  in  FIG. 3 .       

   The Internet client  11  can post data to a CGI script on an HTTP server and receive response from the server. Alternatively, the client can connect to an SMTP server and send out emails to target email addresses.
           27 . Escaping the Internet modem  12  from Internet session streaming socket mode to Internet session command mode.
           Command to Modem: +++   Response from Modem: OK   The sample command is shown as  306  in the command sequence diagram ( FIG. 3 ).         28 . Releasing the socket connection using the “X” command.
           Command to Modem: IRx 0     Response from Modem: OK         29 . Terminating the socket connection using the “D” command.
           Command to Modem: IRD   Response from Modem: OK         30 . Hanging up the Internet modem  12  using standard “ATH” modem command.
           Command to Modem: ATH   Response from Modem: OK           

     FIG. 4  shows the state transition diagram for the Internet modem. The Internet modem transits from Internet modem command mode to Internet modem data mode after a successful “ATD” modem command ( 401 ). It then transits back to Internet modem command mode following an Escape sequence ( 402 ). An “IRC” command negotiates PPP connection and transits the Internet modem to Internet session command mode ( 403 ) and an “IRT” or “IRR” command opens or resumes a TCP socket and transits the Internet modem to Internet session streaming socket mode ( 404 ). An escape sequence transits the Internet modem to Internet session command mode ( 405 ) and an “IRD” command transits the Internet modem to Internet modem command mode ( 406 ). 
   The method described above assumes the negotiating of a PPP connection is using the Password Authentication Protocol. However the method is equally applicable when negotiating of a PPP connection does not use the Password Authentication Protocol. 
   While escaping back to Internet session command mode, another command can be executed. This is shown as  307  in  FIG. 3 . One can create another TCP connection attached to other streaming sockets and perform interaction between the Internet client and a second Internet server by escaping out of one streaming socket. 
     FIG. 5  is a state diagram shows the flow from connecting a TCP socket to a streaming socket, using the streaming socket, and closing the streaming socket (leaving the TCP socket connected). The state transition comprises the following steps:
         Step  501 : Starting streaming socket at an idle state.   Step  502 : When connecting TCP socket to Streaming socket, resetting streaming socket timer counter and streaming socket send buffer to zero.   Step  503 : Streaming socket is now in connected mode.   Step  504 : When escaping from streaming socket mode to idle state, forcing send buffer out TCP socket.   Step  505 : When Internet client sending character, placing received character into streaming socket send buffer and resetting the streaming socket time counter.   Step  506 : If send buffer is not full, keeping the received characters in streaming socket send buffer.   Step  507 : If send buffer is full, forcing send buffer out TCP socket.   Step  508 : If streaming socket send buffer has data, forcing out TCP socket and resetting streaming socket timer counter.   Step  509 : When TCP segment is received on the streaming socket, sending data to Internet client.       
   The sending of TCP packets from the streaming socket buffer is controlled by a Streaming socket timer. The streaming socket timer is usually a value between 1 milliseconds and 5 seconds. When a client sends a character to the streaming socket the timer is reset and starts counting down. If the streaming socket doesn&#39;t receive a character before the timer expires it will send any data waiting to be sent across the TCP socket. This allows data to be packaged up into groups instead of sending one packet for each character or having to know beforehand how many characters the client will be sending. Slower timer values can provide efficiencies even for interactive use. 
   D. Connect to an Http Server 
   In one embodiment, the Internet server  18  is an HTTP server. A simple CGI program on the HTTP server can accept an HTTP GET with data parameters, and process the data, possibly checking for checksums, included in the data, possibly parsing the data for specific information. A response can be generated on the fly and returned in the same HTTP GET transaction, possibly containing status, or configuration information. The data can then be stored in a database or simple file. This also provides a capability for dynamic formatting a presentation of the data in HTML format for a web browser. This can be done through various means, depending on the data storage and the Web tools available. The Internet client  11  established a TCP streaming socket  13  to the HTTP server  18  as described in the above section. 
   Once a TCP streaming socket  13  is established, the Internet client  11  may communicate with the Internet server  18  through the Internet modem  12  as illustrated in the following steps.
         Performing a GET to a CGI program running on the HTTP server by the Internet client;   Sending parameter data to the CGI program by the Internet client;   Parsing the parameter data and saving it to the HTTP server by the CGI program;   Returning data from the CGI program to the Internet client  11 . The data can be viewed through a PC web browser.       

   After the Internet transaction has been performed, the TCP streaming socket  13  can be released and the modem  12  is hang up as described in the above section. 
   E. Connect to a SMTP Server 
   The TCP streaming socket  13  also provides a straightforward way to transmit data with an SMTP server. In another embodiment, the Internet server  18  is an SMTP server. The Internet client  11  uses the Internet modem  12  to send data to a specific email address through the SMTP server. 
   Once a TCP streaming socket  13  is established, the Internet client  11  may communicate with the Internet server  18  through the Internet modem  12  as illustrated in the following steps:
         Entering a return email address by the Internet client  11 ;   Entering one or more target email addresses by the Internet client  11 ;   Sending data to the SMTP server by the Internet client  11 . The data can be retrieved from the mailbox of the target email address.       

   After the Internet transaction has been performed, the TCP streaming socket  13  can be released and the modem  12  is hang up as described in the above section. 
   Although the invention is described herein with reference to the preferred embodiment, one skilled in the art will readily appreciate that other applications may be substituted for those set forth herein without departing from the spirit and scope of the present invention. 
   Accordingly, the invention should only be limited by the Claims included below.