WO2001039478A1

WO2001039478A1 - Method and system for transmitting communication signals through internet and a public switched telephone network

Info

Publication number: WO2001039478A1
Application number: PCT/KR2000/001362
Authority: WO
Inventors: Chang Yoon Joung
Original assignee: Kitel Co., Ltd.
Priority date: 1999-11-26
Filing date: 2000-11-27
Publication date: 2001-05-31
Also published as: AU1899201A; JP2003515980A

Abstract

An Internet-based telephonic service system implements a two-way telephonic communication and call forwarding service between computer terminals and traditional phone instruments through a combination of Internet and a public switched telephone network (PSTN). For performing the two-way telephonic communication service, the system provides each subscribers of this system with a communication number having a format, e.g., a set of digits, that can be entered by an entering unit of the phone instruments. Further, in order to achieve the call forwarding service, if it is received a call request from a calling party of either the computer terminal or the phone instrument, the system first checks whether or not a called party is connected to Internet. If the called party is connected to the Internet, the system establishes a communication channel between the calling party and the called party. If otherwise, the system executes a call forwarding service when the called party registered the call forwarding service. Thus, the system makes a call request corresponding to the registered call forwarding service to thereby call a new called party and establishes a communication channel between the calling party and the new called party.

Description

METHOD AND SYSTEM FOR TRANSMITTING COMMUNICATION

SIGNALS THROUGH INTERNET AND A PUBLIC SWITCHED

TELEPHONE NETWORK

Technical Field

The present invention relates to a communication system based on Internet and a public switched telephone network (PSTN); and, more particularly, to a method and system for implementing a two-way telephonic communication and call forwarding service between computer terminals and traditional phone instruments through combined utilization of the Internet and the PSTN.

Background Art

Nowadays, as communication techniques are globally and exponentially developed, in addition to a conventional communication system using a public switched telephone network (PSTN) through which users can easily communicate with each other by transmitting communication signals from one phone instrument to other phone instruments, other communication systems that make the communication signals be transmitted over Internet have also been developed. In the above, the communication signals include voice data, modem data, or facsimile (fax) data, for example.

One of the communication systems for transmitting the communication signals over the Internet is called a personal computer (PC) -phone that is implemented by using a VoIP (voice over internet protocol). Through the use of the PC-phone having a microphone and a speaker, or a phone attached to a computer terminal, the voice communications between computer terminals can be accomplished by loading and executing a software program that converts received analog signals to digital signals. However, this communication system is not compatible with to the conventional telephonic communication system using the PSTN.

Therefore, recently, in order to make the computer terminal communicate directly with the traditional phone instrument, there has been introduced a communication system employing a gateway unit for transmitting the communication signals from a local phone, e.g., a PC-phone, coupled to the computer terminal to the traditional phone instrument coupled to the PSTN. In this communication system, the gateway unit converts the received telephonic signals from the PC-phone into signals of a format that is compatible with the PSTN to thereby establish a communication channel between the PC-phone and the traditional phone instrument. Since, however, the above communication system only implements the telephonic communication channel from the PC-phone to the traditional phone instrument, the traditional phone instrument users do not have any means capable of gaining an access to the PC-phone.

Disclosure of Invention

It is, therefore, a primary object of the present invention to provide a method and system capable of implementing a telephone-to-computer communication service through combined utilization of Internet and a PSTN by assigning a communication number, which is available to traditional phone instrument users, to a subscriber of this system so that the phone instrument users can communicate with the subscriber by directly entering the communication number through a data-entering unit of the phone instrument, e.g.. a dialer. Another object of the present invention is to provide a call forwarding service to the subscribers of the inventive communication system.

In accordance with one aspect of the present invention, there is provided a method for transmitting communication signals between computer terminals and phone instruments across a computer-based communications network and a public switched telephone network (PSTN), which comprises the steps of:

(a) receiving a call request from a calling party, wherein the call request is placed by inputting a communication number identifying a called party;

(b) checking whether or not the called party is connected to the computer-based communications network;

(c) if the called party is connected to the computer-based communications network, establishing a communication channel between the calling party and the called party;

(d) if the called party is disconnected from the computer-based communications network, executing a call forwarding service when the called party is registered for the call forwarding service;

(e) making a call request corresponding to the registered call forwarding service to thereby call a new called party registered as a target place of the call forwarding service; and

(f) establishing a communication channel between the calling party and the new called party. In accordance with another aspect of the present invention, there is provided a system for transmitting communication signals between computer terminals and phone instruments across a computer-based communications network and a public switched telephone network (PSTN), comprising: a gateway unit for making a data channel between the computer terminal and the phone instrument by translating the communication signals received from either the computer terminals or the phone instruments into signals of a format compatible with either the PSTN or the computer-based communications network; a gatekeeper for establishing and controlling a call channel between the computer terminals and the phone instruments based on calling party information and called party information provided from the computer terminals or the phone equipments which can be a calling party or a called party, wherein the calling party information identifies the calling party making a call request and the called party information verifies the called party called by the calling party; and a server for assigning a communication number to each of subscribers of the system using the computer terminals, performing operations related to identifying and verifying said each of the subscribers based on subscriber information for said each of the subscriber stored therein, and providing a call forwarding service to said each of the subscriber, wherein the communication number is used to identify said each of the subscribers and make a call request to said each of the subscribers.

Brief Description of Drawings

The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

Fig. 1 illustrates a communication service system in which a preferred embodiment of the present invention is implemented;

Fig. 2 shows a flow chart describing a computer-to-telephone communication procedure in accordance with the present invention; Fig. 3 provides a flow chart explaining a computer-to-computer communication procedure in accordance with the present invention; and

Fig. 4 describes a flow chart illustrating a telephone-to-computer communication procedure in accordance with the present invention.

Best Mode for Carrying Out the Invention

Hereinafter, with reference to the drawings, the embodiments of the present invention will be explained in detail. Referring to Fig. 1 , there is illustrated a communication service system which comprises a public switched telephone network (PSTN) 20, a switch 30, an inventive telephonic service system 40 and a computer-based communications network, e.g., Internet 50, so as to perform telephonic communications between conventional phone instruments, e.g., 10A and 10B, and computer terminals, e.g., PCs 60A and 60B. Herein, the computer terminal includes a headset and a microphone to accomplish the telephonic communication.

Moreover, the telephonic service system 40 includes a gateway unit 41 , a gatekeeper 42, a storage unit 43, a UMS (unified messaging system) server 44, a messenger server 45, a database server 46 and a network accessed subscriber management server 47.

The PSTN 20 provides a telephonic communication channel to a multiplicity of phone instrument users such as wired, wireless (cellular, mobile), analog and digital telephone users for the purpose generally known in the art. The switch 30 is connected between the PSTN 20 and the gateway unit

41 of the telephonic service system 40 so as to transfer telephonic signals to and from the phone instrument, 10A or 10B, and the PC, 60A or 60B. In general, more than one switch is connected through transmission trunks installed to connect central offices (not shown) on the PSTN 20. The gateway unit 41 is connected to the switch 30, and the Internet 50 or the UMS server 44; and, under the control of the gatekeeper 42, establishes a telephonic communication channel between the phone instrument, 10A or 10B, attached to the PSTN 20 and the PC, 60A or 60B, connected to the Internet 50 by converting telephonic communication signals received from the PC via the Internet 50 into signals of a format compatible with the PSTN 20 or telephonic communication signals received from the phone instrument across the PSTN 20 into signals of a format compatible with the Internet 50. In accordance with another embodiment of the present invention, more than one gateway unit can be connected to the PSTN 20 according to regional distribution although there is shown only one gateway unit in Fig. 1.

Further, to control the operation of gateway unit 41, the gatekeeper 42 controls operations of establishing a call channel, e.g., between the phone instrument, 10A or 10B, and the PC, 60A or 60B, or between two PCs, e.g., 60 A and 60B.

Under the control of the gatekeeper 42, the storage unit 43 stores a telephonic communication record such as a conversation time of a subscriber of the telephonic service system 40 when the subscriber uses the telephonic service provided by the system 40.

Through the UMS server 44, a certain subscriber of the telephonic service system 40 can leave messages to other subscribers when it is impossible to establish a telephonic communication channel between the certain subscriber and the other subscribers.

Meanwhile, the messenger server 45 controls operations of performing the telephonic communication service provided by the telephonic service system 40 in cooperation with the other servers, e.g., the database server 46 and the network accessed subscriber management server 47. In accordance with the preferred embodiment of the present invention, the messenger server 45 can be constituted with more than one sub-server so as to distribute its traffic and each sub-server manages a multiplicity of, e.g., 1000, subscribers accessed to the telephonic service system 40.

The network accessed subscriber management server 47 manages subscribers connected to the telephonic service system 40 via the Internet 50.

The database server 46 manages subscriber information of all of subscribers registered to the telephonic service system 40.

When a subscriber registers at the telephonic service system 40, the subscriber can get a communication number assigned thereto from the telephonic service system 40. After the registration, the communication number is used as an identifier whenever the subscriber tries to access to the telephonic service system 40.

In accordance with the present invention, the communication number can be entered by any traditional phone instrument having a data-entering unit, e.g., a dialer. Therefore, the communication number assigned to each subscriber of the inventive telephonic service system 40 includes a set of digits by which each subscriber is distinguished from other subscribers. For instance, the communication number is represented as yyyy-zzzz, wherein y and z are selected from 0 to 9 and the number of digits consisting of the communication number is variable.

In accordance with another embodiment of the present invention, the communication number can be substituted by an e-mail address, a registered URL (universal resource locator), a traditional ID address, a conventional telephone number which has already been assigned to each traditional phone user, or the like. That is, the communication number may have any format that can distinguish each subscriber from other subscribers and can be entered by any traditional phone instrument. However, it may be most preferable that the communication number is represented by a set of digits having a format similar to a conventional telephone number.

Therefore, when a traditional phone user tries to have a telephonic communication with a desired subscriber of the telephonic service system 40, the phone user first enters a system calling number that provides the phone user with an access to the telephonic service system 40 and then inputs a communication number of the desired subscriber to call the desired subscriber. According to a configuration of the communication service system, the phone user can successively or separately enter the system calling number and the communication number.

On the other hand, if a subscriber of the telephonic service system 40 tries to call another subscriber by using a computer terminal, the subscriber can call the called party by only inputting a communication number of the called party without entering the system call number. However, when the called party uses its preoccupied traditional telephone number, e.g., its wired phone number or cellular phone number, as its communication number, then in order to distinguish the PC calling from the traditional telephone calling, the subscriber enters, through the use of a data entering unit of the computer terminal, the traditional telephone subscriber number together with, e.g., a country code, or the country code and an area code according to a type of a traditional telephone to be called, e.g., a wired or mobile phone, wherein the country code verifies a desired country and the area code represents a desired region in the desired country.

Further to the above communication number assignment to each subscriber of the telephonic service system 40 in accordance with the present invention, referring to Figs. 2 to 4, there are illustrated flow charts describing telephonic communication procedures providing a call forwarding service and a UMS service in accordance with the present invention. Hereinafter, their operations will be explained with reference to the communication service system described in Fig. 1. In Figs. 2 to 4, some steps are not unique to the present invention but are included to help for a full understanding of the present invention.

First, referring to Fig. 2, there is shown a computer-to-telephone communication procedure in accordance with the present invention.

Once a certain subscriber tries to have an access to the telephonic service system 40 by executing a client program and entering its communication number and password through the use of a client terminal, e.g., the first PC 60A, the messenger server 45 performs an authentication process of the certain subscriber in cooperation with the database server 46 based on the communication number and password.

After the certain subscriber is successfully authenticated, in step S21 , the certain subscriber, i.e., a calling party, generates a call request to the gatekeeper 42 by providing a telephone number of a called party, e.g., the first phone instrument 10A, through the use of the client program being executed on the first PC 60A. In this step, the gatekeeper 42 can get calling party information, e.g., an IP address assigned to the first PC 60A and the communication number and password of the certain subscriber, and called party information, e.g., the telephone number, provided from the first PC 60A.

In step S22, the gatekeeper 42 requests the authentication of the calling party to the messenger server 45 based on the calling party information; and checks whether the called party is within a communication service extent of the telephonic service system 40 or not in cooperation with the messenger server 45 based on the called party information.

Through the above process in step S22, if the calling party is authenticated and the called party is verified as included in the communication service extent, the first PC 60A makes a dialing forwarded to the called party via the gateway unit 41 and the PSTN 20 in step S23.

Then, in step S24, it is checked whether or not a communication channel is established between the calling party and the called party.

If the communication channel is established via the Internet 50, the gateway unit 41 and the PSTN 20, the calling party, i.e., the first PC 60A, can make a telephonic communication with the called party, i.e.. the phone instrument 10 A.

On the other hand, if the communication channel is not established, the telephonic service system 40 provides a connection failure message to the first PC 60A and, then, this calling procedure is terminated.

As shown in Fig. 2, when the calling party, a PC or a phone instrument, tries to make a telephonic communication channel with a phone instrument, the call forwarding service and the UMS service are not provided to the phone instrument regardless whether or not the called party, i.e., the phone instrument, is a registered subscriber of the telephonic service system 40. Therefore, the communication procedure shown in Fig. 2 is similar to those of other communication service systems in the prior art. Referring to Fig. 3, there is described a computer-to-computer communication procedure in accordance with the present invention.

First, as shown in Fig. 2, once the certain subscriber is successfully authenticated by the messenger server 45 with the help of the database server 46 based on its communication number and password inputted via the first PC 60A, in step S312, the certain subscriber, i.e., a calling party, generates a call request to the gatekeeper 42 by providing a communication number of a called party through the use of the client program being executed on the first PC 60A. In this step, the gatekeeper 42 can get calling party information, e.g., an IP address assigned to the first PC 60A and the communication number and password of the certain subscriber, and called party information, e.g., the communication number, provided from the first PC 60A.

In step S314, the gatekeeper 42 requests the authentication of the calling party to the messenger server 45 based on the calling party information.

Once the calling party is authenticated and, in step S316, the gatekeeper 42 asks the messenger server 45 to check whether or not the called party is connected to the telephonic service system 40 in cooperation with the network accessed subscriber management server 47.

As a result of the above checking process, if the called party is determined as, e.g., the second PC 60B connected to the telephonic service system 40, the gatekeeper 42 obtains an IP address of the called party, i.e.. the second PC 60B, from the messenger server 45 and this procedure goes to step S318. On the other hand, if the called party is not verified in the above checking process, this procedure proceeds to step S324.

In step S318, the gatekeeper 42 requests the messenger server 45 to check whether the second PC 60B is in a call-receivable state or not.

If the second PC 60B is not in the call-receivable state, this procedure proceeds to step S334 and the first PC 60A is connected to the UMS server 44. On the other hand, if it is determined that the second PC 60B is in the call-receivable state, the first PC 60A makes a dialing forwarded to the second PC 60B via the Internet 50 in step S320.

Then, in step S322, it is checked whether or not a communication channel is established between the first PC 60 A and the second PC 60B.

If it is checked that the communication channel is established between the first and the second PCs 60A and 60B via the Internet 50, the first PC 60A can make a telephonic communication with the second PC 60B.

On the other hand, if it is checked that the communication channel is not established, this procedure goes to step S334 and the first PC 60 A can be connected to the UMS server 44 to leave messages on a storage unit (not shown) of the UMS server 44.

In the meantime, in step S324, the messenger server 45 checks whether the called party is a registered subscriber of the telephonic service system 40. If it is found in step S324 that the called party is not a registered subscriber, the telephonic service system 40 provides a connection failure message to the first PC 60A and this calling procedure is terminated.

On the other hand, if the called party is a registered subscriber, the messenger server 45 examines in step S326 whether or not this call procedure is the first PC call trial corresponding to the PC call request made in step S312.

If the PC call trial is not a first time, this procedure goes to step S334 to allow the first PC 60A to leave messages for the called party on the storage unit of the UMS server 44.

If it is determined in step S326 that the first PC 60A has made only one PC call trial corresponding to the PC call request in step S312, in step S328, the messenger server 45 verifies whether or not the called party is registered for the call forwarding service.

When the called party is not registered for the call forwarding service, this calling procedure moves to step S334 whose operation is described above. On the other hand, if the called party is registered for the call forwarding service and a target place of the call forwarding service is a PC, this procedure goes to step S314 to thereby repeat the PC calling procedure described above.

Meanwhile, the target place of the call forwarding service is a phone instrument, the first PC 60A makes a dialing forwarded to the target phone instrument via the gateway unit 41 and the PSTN 20 in step S330.

Then, in step S332, it is checked whether or not a communication channel is established between the first PC 60A and the target phone instrument. If the communication channel is established via the Internet 50, the gateway unit 41 and the PSTN 20, the first PC 60A can make a telephonic communication with the target phone instrument.

Referring to Fig. 4, there is described a flow chart illustrating a telephone-to-computer communication procedure in accordance with the present invention. In order to establish a communication channel connected to the telephonic service system 40, a user of a phone instrument, e.g., 10A, first calls the telephonic service system 40 by entering a system call number assigned to the telephonic service system 40 through the use of a dialer of the phone instrument 10 A in step S411. Then, in step S412, the phone instrument user can get an ARS (audio response system) service provided from the telephonic service system 40.

In step S413, the phone instrument user selects a PC call service according to directions of the ARS (not shown) and originates a call to a called party by entering a communication number of the called party. In accordance with another embodiment of the present invention, without steps S412 and S413, the phone instrument user directly inputs the communication number of the called party to make the PC call.

Once the phone instrument 10A and the telephonic service system 40 are connected and the communication number is inputted, in step S416, the gateway unit 41 asks the messenger server 45 via the gatekeeper 42 to check whether or not the called party is connected to the telephonic service system 40 based on the communication number in cooperation with the network accessed subscriber management server 47.

As a result of the above checking process, if the called party is determined as, e.g., the first PC 60A connected to the telephonic service system 40, the gatekeeper 42 obtains an IP address of the called party, i.e., the first PC 60A. from the messenger server 45 and this procedure goes to step S418. On the other hand, if the called party is not verified in the above checking process, this procedure proceeds to step S424. In step S418, the gatekeeper 42 requests the messenger server 45 to check whether the first PC 60A is in a call-receivable state or not.

As the checking result of step S418, if it is found that the first PC 60A is not in the call-receivable state, the phone instrument 10A is connected to the UMS server 44 to thereby leave messages for the first PC 60A on the storage unit of the UMS server 44.

On the other hand, if it is determined that the first PC 60A is in the call- receivable state, the gateway unit 41 makes a dialing forwarded to the first PC 60A via the Internet 50 in step S420.

Then, as a checking result in step S422, if it is determined that the communication channel is established between the phone instrument 10A and the first PC 60 A, the phone instrument 10A can achieve a telephonic communication with the first PC 60A via the PSTN 20, the switch 30, the gateway unit 41 and the Internet 50.

On the other hand, if it is determined that the communication channel is not established as the checking result of step S422, this procedure goes to step S434 and the phone instrument 10A is connected to the UMS server 44. Meanwhile, if the called party is determined in step S416 that it is not connected to the telephonic service system 40, in step S424, the messenger server 45 checks whether the called party is a registered subscriber of the telephonic service system 40.

If it is found in step S424 that the called party is not the registered subscriber, the telephonic service system 40 provides a connection failure message to the phone instrument 10A and this calling procedure is terminated.

On the other hand, if the called party is a registered subscriber, the messenger server 45 examines in step S426 whether or not this call procedure is the first PC call trial corresponding to the PC call request made in step S413. If the PC calling trial is not the first trial, this procedure goes to step

S434 to allow the phone instrument user to leave messages for the called party on the storage unit of the UMS server 44.

If it is determined in step S426 that the phone instrument 10A has made only one PC call trial, in step S428, the messenger server 45 verifies whether or not the called party is registered for the call forwarding service.

When the called party is not registered for the call forwarding service, this calling procedure moves to step S434 whose operation is described above.

On the other hand, if the called party is registered for the call forwarding service and a target place of the call forwarding service is a PC, this procedure goes to step S416 to thereby repeat the PC calling procedure described above.

Meanwhile, if the target place of the call forwarding service is a phone instrument, the phone instrument 10A makes a dialing forwarded to another phone instrument via the PSTN 20 in step S430.

Then, in step S432, it is checked whether or not the communication channel is established between the phone instrument 10A and the other phone instrument. 5 If the communication channel is established, the phone instrument 10A can make a telephonic communication with the other phone instrument via the PSTN 20.

On the other hand, if the communication channel is not established, this calling procedure is terminated, l o In the above, when the phone instrument and the computer terminal are connected to perform the telephonic communication via the PSTN 20 and the Internet 50, the gateway unit 41 continuously monitors whether the phone instrument and the computer terminal are accessible.

If both of them are continuously accessible, the gateway unit 41 15 continuously performs an intermediating function between the phone instrument and the computer terminal until at least one of the phone instrument and the computer terminal becomes inaccessible.

Then, if it is detected that at least one of them is not accessible, the gateway unit 41 informs the disconnection to the gatekeeper 42 and the 0 gatekeeper 42 stores its conversation record in the storage unit 43.

In another embodiment of the present invention, the calling party can determine whether or not to receive the call forwarding service established for the called party.

Through the above communication procedures described in Figs. 2 to 4 5 in accordance with the present invention, the computer-to-telephone, computer- to-computer and telephone-to-computer communications can be implemented through the combination of the PSTN 20 and Internet 50. Therefore, the subscribers of the telephonic service system 40 can gain an access to other telephonic systems and be also accessible in any places once they have an 0 access to the telephonic service system 40.

Although the present invention is only illustrated related to the Internet, it can be adapted to various different types of computer-based communications networks such as LANs and WANs. Moreover, it is noted that the present invention can be also adapted to a fax, a modem, or the like since the 5 communication signals include modem data, fax data, or the like. In this case, the procedure for originating a call for fax or modem transmission is similar to setting up of a telephone call, as described above, except that the end-to-end delay of the communication signals is, typically, not as important as it is for voice communications.

Furthermore, this system can be also adapted to a video-telephone such as an IMT-2000 (International Mobile Telecommunications-2000) based on the Internet.

Also, even though the present invention shows the telephonic communication service, it will be understood by persons skilled in the relevant art that the telephonic service system can provide its subscribers with various additional services well known in the art by connecting thereto various service providing servers.

While the present invention has been described with respect to the particular embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. A method for transmitting communication signals between computer terminals and phone instruments across a computer-based communications network and a public switched telephone network (PSTN), which comprises the steps of:

(e) making a call request corresponding to the registered call forwarding service to thereby call a new called party registered as a target place of the call forwarding service; and (f) establishing a communication channel between the calling party and the new called party.

2. The method of claim 1, wherein the calling party is either a computer terminal or a phone instrument.

3. The method of claim 2, wherein the step (d) further includes the step of allowing the calling party to leave messages for the called party on a storage unit if the called party is not registered for the call forwarding service or the calling party does not select the call forwarding service.

4. The method of claim 3, wherein, if the new called party is a computer terminal, the step (f) includes the steps of:

(fl l) if the new called party is connected to the computer-based communications network, connecting the calling party and the new called party; and

(fl2) if the new called party is disconnected from the computer-based communications network, allowing the calling party to leave messages for the new called party on the storage unit.

5. The method of claim 3, wherein, if the new called party is a phone instrument, the step (f) includes the steps of: (f21) if the new called party is connected to the PSTN, connecting the calling party to the new called party; and

(f22) if the new called party is disconnected from the PSTN, terminating the calling procedure.

6. The method of claim 1, wherein the communication number has a format that can be entered by an entering unit of the phone instrument.

7. The method of claim 6, wherein the communication number is a set of digits.

8. The method of claim 7, wherein a telephone number preoccupied by the called party is used as the communication number.

9. The method of claim 1, wherein the computer-based communications network is Internet.

10. The method of claim 9, wherein the phone instrument is selected from a group including a wired phone, a mobile phone, a facsimile and a modem.

11. A system for transmitting communication signals between computer terminals and phone instruments across a computer-based communications network and a public switched telephone network (PSTN), comprising: means for making a data channel between the computer terminal and the phone instrument by translating the communication signals received from either the computer terminals or the phone instruments into signals of a format compatible with either the PSTN or the computer-based communications network; means for establishing and controlling a call channel between the computer terminals and the phone instruments based on calling party information and called party information provided from the computer terminals or the phone equipments which can be a calling party or a called party, wherein the calling party information identifies the calling party making a call request and the called party information verifies the called party called by the calling party; and means for assigning a communication number to each of subscribers of the system, performing operations related to identifying and verifying said each of the subscribers based on subscriber information for said each of the subscribers, and providing a call forwarding service to said each of the subscribers, wherein the communication number is used to identify said each of the subscribers and make a call request to said each of the subscribers.

12. The system according to claim 11, further comprising means for providing said each of the subscribers with a predetermined amount of memory storing messages supplied from calling parties which call said each of the subscribers.

13. The system according to claim 12, wherein the communication number has a format that can be entered by an entering unit of the phone instrument.

14. The system according to claim 13, wherein the communication number is a set of digits.

15. The system according to claim 14, wherein a telephone number preoccupied by said each of the subscribers is used as the communication number.

16. The system according to claim 15. wherein the computer-based communications network is Internet.

17. The system according to claim 16, wherein the phone instrument is selected from a group including a wired phone, a mobile phone, a facsimile and a modem.